21 post tagged


Target audience parsing in VK

Estimated read time – 5 min

When posting ads some platforms allow uploading the list of people who will see the ad in audience settings. There are special tools to parse ids from public pages but it’s much more interesting (and cheaper) to do it manually with Python and VK API. Today we will tell how we parsed the target audience for the LEFTJOIN promotional campaign and uploaded it to the advertising account.

Parsing of users

To send requests we will need a user token and the list of VK groups whose participants we want to get. We collected about 30 groups related to analytics, BI tools and Data Science.

import requests 
import time 

group_list = ['datacampus', '185023286', 'data_mining_in_action', '223456', '187222444', 'nta_ds_ai', 'business__intelligence', 'club1981711', 'datascience', 'ozonmasters', 'businessanalysts', 'datamining.team', 'club.shad', '174278716', 'sqlex', 'sql_helper', 'odssib', 'sapbi', 'sql_learn', 'hsespbcareer', 'smartdata', 'pomoshch_s_spss', 'dwhexpert', 'k0d_ds', 'sql_ex_ru', 'datascience_ai', 'data_club', 'mashinnoe_obuchenie_ai_big_data', 'womeninbigdata', 'introstats', 'smartdata', 'data_mining_in_action', 'dlschool_mipt'] 

token = 'your_token'

A request for getting the participants of VK groups will return a maximum of 1000 lines, to get the next 1000 ones we need to increment an offset parameter by 1. But we need to know when to stop incrementing so we will write a function that accepts an id of the group, receives the information about the number of group’s participants and returns the maximum number for the offset – the ratio of the total number of participants to 1000 as we can only get 1000 persons at a time.

def get_offset(group_id): 
    count = requests.get('https://api.vk.com/method/groups.getMembers', 
           'group_id': group_id, 
    return count // 1000

In the next step, we will write a function that accepts the group’s ID, collects all the subscribers into a list and returns it. To do this we will send requests for receiving 1000 people till the offset is over, enter the data into the list and return it. When parsing each person, we will additionally check their last visit date and if they have not logged in since the middle of November, we won’t add them. The time is indicated in unixtime format.

def get_users(group_id): 
    good_id_list = [] 
    offset = 0 
    max_offset = get_offset(group_id) 
    while offset < max_offset: 
        response = requests.get('https://api.vk.com/method/groups.getMembers', 
        'group_id': group_id, 
        'fields':'last_seen' }).json()['response'] 
        offset += 1 
        for item in response['items']: 
                if item['last_seen']['time'] >= 1605571200:
            except Exception as E: 
    return good_id_list

Now we will parse all groups from the list, collect the participants, and add them into the all_users list. In the end, we will transfer the list into a set and then back into a list to get rid of the duplicates as the same people might have been members of different groups. After parsing each group, we will pause the program for a second to prevent reaching the requests limit.

all_users = [] 

for group in group_list: 
        users = get_users(group) 
    except KeyError as E: 
        print(group, E) 

all_users = list(set(all_users))

The last step will be writing each user to a file from a new line.

with open('users.txt', 'w') as f: 
    for item in all_users: 
        f.write("%s\n" % item)

Audience in the advertising account from a file

Let’s open our VK advertising account and choose a “Retargeting” tab. Here we will find the “Create audience” button:


After clicking it, a new window will pop up where we will be able to choose a file as a source and indicate the name of the audience.


The audience will be available some seconds after loading. First 10 minutes it will be indicated that the audience is too small, this is not true, and the panel will refresh soon if your audience really contains more than 100 people.



Let’s compare the average cost of the attracted participant in our group when using the ad with automatic audience targeting and the ad with the audience that we have scraped. In the first case, the average cost is 52.4 rubles, in the second case 33.2 rubles. The selection of a quality audience by parsing data from VK helped us to reduce the average costs by 37%.
We have prepared this post for our advertising campaign:
Hey! You see this ad because we have parsed your id and made a file targeting in VK advertising account. Do you want to know how to do this?
LEFTJOIN – a blog about analytics, visualizations, Data Science and BI. A blog contains a lot of material on different BI and SQL tools, data visualizations and dashboards, work with different APIs (from Google Docs to social networks to the amateurs of beer) and interesting Python libraries.

 No comments    236   3 mon   api   python   VK   VK api

How to build a dashboard with Bootstrap 4 from scratch (Part 2)

Estimated read time – 11 min


Previously we shared how to use Bootstrap components in building dashboard layout and designed a simple yet flexible dashboard with a scatter plot and Russian map. In today’s material, we will continue adding more information, explore how to make Bootstrap tables responsive, and cover some complex callbacks for data acquisition.

Constructing Data Tables

All the code for populating our tables with data will be stored in get_tables.py , while the layout components areoutlined in  application.py. This article will cover the process of creating the table with top Russian Breweries, however, you can find the code for creating the other three on Github.

Data in the Top Breweries table can be filtered by city name in the dropdown menu, but the data collected in Untappd is not equally structured. Some city names are written in Latin, others in Cyrillic. So the challenge is to make the names equal for SQL queries, and here is where Google Translate comes to the rescue. Though we sill have to manually create a dictionary of city names, since for example “Москва” can be written as “Moskva” and not “Moscow”. This dictionary will be used later for mapping our DataFrame before transforming it into a Bootstrap table.

import pandas as pd
import dash_bootstrap_components as dbc
from clickhouse_driver import Client
import numpy as np
from googletrans import Translator

translator = Translator()

client = Client(host='', user='default', password='', port='9000', database='')

city_names = {
   'Moskva': 'Москва',
   'Moscow': 'Москва',
   'СПБ': 'Санкт-Петербург',
   'Saint Petersburg': 'Санкт-Петербург',
   'St Petersburg': 'Санкт-Петербург',
   'Nizhnij Novgorod': 'Нижний Новгород',
   'Tula': 'Тула',
   'Nizhniy Novgorod': 'Нижний Новгород',

Top Breweries Table

This table displays top 10 Russian breweries and their position change according to the rating. Simply put, we need to compare data for two periods, that’s [30 days ago; today] and [60 days ago; 30 days ago]. With this in mind, we will need the following headers: ranking, brewery name, position change, and number of check-ins.
Create the  get_top_russian_breweries function that would make queries to the Clickhouse DB, sort the data and return a refined Pandas DataFrame. Let’s send the following queries to obtain data for the past 30 and 60 days, ordering the results by the number of check-ins.

Querying data from the Database

def get_top_russian_breweries(checkins_n=250):
   top_n_brewery_today = client.execute(f'''
      SELECT  rt.brewery_id,
              beer_pure_average_mult_count/count_for_that_brewery as avg_rating,
              count_for_that_brewery as checkins FROM (
              dictGet('breweries', 'brewery_name', toUInt64(brewery_id)) as brewery_name,
              sum(rating_score) AS beer_pure_average_mult_count,
              count(rating_score) AS count_for_that_brewery
          FROM beer_reviews t1
          ANY LEFT JOIN venues AS t2 ON t1.venue_id = t2.venue_id
          WHERE isNotNull(venue_id) AND (created_at >= (today() - 30)) AND (venue_country = 'Россия') 
          GROUP BY           
              brewery_name) rt
      WHERE (checkins>={checkins_n})
      ORDER BY avg_rating DESC
      LIMIT 10

top_n_brewery_n_days = client.execute(f'''
  SELECT  rt.brewery_id,
          beer_pure_average_mult_count/count_for_that_brewery as avg_rating,
          count_for_that_brewery as checkins FROM (
          dictGet('breweries', 'brewery_name', toUInt64(brewery_id)) as brewery_name,
          sum(rating_score) AS beer_pure_average_mult_count,
          count(rating_score) AS count_for_that_brewery
      FROM beer_reviews t1
      ANY LEFT JOIN venues AS t2 ON t1.venue_id = t2.venue_id
      WHERE isNotNull(venue_id) AND (created_at >= (today() - 60) AND created_at <= (today() - 30)) AND (venue_country = 'Россия')
      GROUP BY           
          brewery_name) rt
  WHERE (checkins>={checkins_n})
  ORDER BY avg_rating DESC
  LIMIT 10

Creating two DataFrames with the received data:

top_n = len(top_n_brewery_today)
column_names = ['brewery_id', 'brewery_name', 'avg_rating', 'checkins']

top_n_brewery_today_df = pd.DataFrame(top_n_brewery_today, columns=column_names).replace(np.nan, 0)
top_n_brewery_today_df['brewery_pure_average'] = round(top_n_brewery_today_df.avg_rating, 2)
top_n_brewery_today_df['brewery_rank'] = list(range(1, top_n + 1))

top_n_brewery_n_days = pd.DataFrame(top_n_brewery_n_days, columns=column_names).replace(np.nan, 0)
top_n_brewery_n_days['brewery_pure_average'] = round(top_n_brewery_n_days.avg_rating, 2)
top_n_brewery_n_days['brewery_rank'] = list(range(1, len(top_n_brewery_n_days) + 1))

And then calculate the position change over the period of time for each brewery received. With the try-except block, we will handle exceptions, in case, if a brewery was not yet in our database 60 days ago.

rank_was_list = []
for brewery_id in top_n_brewery_today_df.brewery_id:
           top_n_brewery_n_days[top_n_brewery_n_days.brewery_id == brewery_id].brewery_rank.item())
   except ValueError:
top_n_brewery_today_df['rank_was'] = rank_was_list

Now we iterate over the columns with current and former positions. If there is no hyphen contained in, we will append an up or down arrow depending on the change.

diff_rank_list = []
for rank_was, rank_now in zip(top_n_brewery_today_df['rank_was'], top_n_brewery_today_df['brewery_rank']):
   if rank_was != '–':
       difference = rank_was - rank_now
       if difference > 0:
           diff_rank_list.append(f'↑ +{difference}')
       elif difference < 0:
           diff_rank_list.append(f'↓ {difference}')

Finally, replace DataFrame headers, inserting the column with current ranking positions, where the top 3 will be displayed with the trophy emoji.

df = top_n_brewery_today_df[['brewery_name', 'avg_rating', 'checkins']].round(2)
df.insert(2, 'Position change', diff_rank_list)
df.insert(0, 'RANKING', list('🏆 ' + str(i) if i in [1, 2, 3] else str(i) for i in range(1, len(df) + 1)))

return df

Filtering data by city name

One of the main tasks we set before creating this dashboard was to find out what are the most liked breweries in a certain city. The user chooses a city in the dropdown menu and gets the results. Sound pretty simple, but is it that easy?
Our next step is to write a script that would update data for each city and store it in separate CSV files. As we mentioned earlier, the city names are not equally structured, so we need to use Google Translator within the if-else block, and since it may not convert some names to Cyrillic we need to explicitly specify such cases:

en_city = venue_city
if en_city == 'Nizhnij Novgorod':
      ru_city = 'Нижний Новгород'
elif en_city == 'Perm':
      ru_city = 'Пермь'
elif en_city == 'Sergiev Posad':
      ru_city = 'Сергиев Посад'
elif en_city == 'Vladimir':
      ru_city = 'Владимир'
elif en_city == 'Yaroslavl':
      ru_city = 'Ярославль'
      ru_city = translator.translate(en_city, dest='ru').text

Then we need to add both city names in English and Russian to the SQL query, to receive all check-ins sent from this city.

WHERE (rt.venue_city='{ru_city}' OR rt.venue_city='{en_city}')

Finally, we export received data into a CSV file in the following directory – data/cities.

df = top_n_brewery_today_df[['brewery_name', 'venue_city', 'avg_rating', 'checkins']].round(2)
df.insert(3, 'Position Change', diff_rank_list)
df['CITY'] = df['CITY'].map(lambda x: city_names[x] if (x in city_names) else x)
df['CITY'] = df['CITY'].map(lambda x: translator.translate(x, dest='en').text)
df.to_csv(f'data/cities/{en_city}.csv', index=False)
print(f'{en_city}.csv updated!')

Scheduling Updates

We will use the apscheduler library to automatically run the script and refresh data for each city in all_cities every day at 10:30 am (UTC).

from apscheduler.schedulers.background import BackgroundScheduler
from get_tables import update_best_breweries

all_cities = sorted(['Vladimir', 'Voronezh', 'Ekaterinburg', 'Kazan', 'Red Pakhra', 'Krasnodar',
             'Kursk', 'Moscow', 'Nizhnij Novgorod', 'Perm', 'Rostov-on-Don', 'Saint Petersburg',
             'Sergiev Posad', 'Tula', 'Yaroslavl'])

scheduler = BackgroundScheduler()
@scheduler.scheduled_job('cron', hour=10, misfire_grace_time=30)
def update_data():
   for city in all_cities:

Table from DataFrame

get_top_russian_breweries_table(venue_city, checkins_n=250)  will accept venue_city and checkins_n generating a Bootstrap Table with the top breweries. The second parameter value, checkins_n can be changed with the slider. If the city name is not specified, the function will return top Russian breweries table.

if venue_city == None: 
      selected_df = get_top_russian_breweries(checkins_n)
      en_city = venue_city

In other case the DataFrame will be constructed from a CSV file stored in data/cities/. Since the city column still may contain different names we should apply mapping and use a lambda expression with the map() method. The lambda function will compare values in the column against keys in city_names and if there is a match, the column value will be overwritten.
For instance, if df[‘CITY’] contains “СПБ”, a frequent acronym for Saint Petersburg, the value will be replaced, while for “Воронеж” it will remain unchanged.
And last but not least, we need to remove all duplicate rows from the table, add a column with a ranking position and return the first 10 rows. These would be the most liked breweries in a selected city.

df = pd.read_csv(f'data/cities/{en_city}.csv')     
df = df.loc[df['CHECK-INS'] >= checkins_n]
df.drop_duplicates(subset=['NAME', 'CITY'], keep='first', inplace=True)  
df.insert(0, 'RANKING', list('🏆 ' + str(i) if i in [1, 2, 3] else str(i) for i in range(1, len(df) + 1)))
selected_df = df.head(10)

After all DataFrame manipulations, the function returns a simply styled Bootstrap table of top breweries.

Bootstrap table layout in DBC

table = dbc.Table.from_dataframe(selected_df, striped=False,
                                bordered=False, hover=True,
                                style={'background-color': '#ffffff',
                                       'font-family': 'Proxima Nova Regular',
                                       'fontSize': '12px'},
                                className='table borderless'

return table

Layout structure

Add a Slider and a Dropdown menu with city names in application.py

To learn more about the Dashboard layout structure, please refer to our previous guide

checkins_slider_tab_1 = dbc.CardBody(
                                   html.H6('Number of check-ins', style={'text-align': 'center'})),
                                       loading_state={'is_loading': True},
                                       marks={i: i for i in list(range(0, 251, 25))}
                           style={'max-height': '80px', 
                                  'padding-top': '25px'

top_breweries = dbc.Card(
                           html.H6('Filter by city', style={'text-align': 'center'}),
                               options=[{'label': i, 'value': i} for i in all_cities],
                               placeholder='Select city',
                               style={'font-family': 'Proxima Nova Regular'}
                   html.P(id="tab-1-content", className="card-text"),

We’ll also need to add a callback function to update the table by dropdown menu and slider values:

   Output("tab-1-content", "children"), [Input("city_menu", "value"),
                                         Input("checkin_n_tab_1", "value")]
def table_content(city, checkin_n):
   return get_top_russian_breweries_table(city, checkin_n)

Tada, the main table is ready! The dashboard can be used to receive up-to-date info about best Russian breweries, beers, and its rating across different regions, and help to make a better choice for an enjoyable tasting experience.

2-17.png http://dashboard-final-en.us-east-2.elasticbeanstalk.com/

View the code on GitHub

 No comments    245   10 mon   BI-tools   bootstrap   dash   plotly   python

Collecting Social Media Data for Top ML, AI & Data Science related accounts on Instagram

Estimated read time – 9 min

Instagram is in the top 5 most visited websites, perhaps not for our industry. Nevertheless, we are going to test this hypothesis using Python and our data analytics skills. In this post, we will share how to collect social media data using the Instagram API.

Data collection method
The Instagram API won’t let us collect data about other platform users for no reason, but there is always a way. Try sending the following request:


The request returns a JSON object with detailed user information, for instance, we can easily get an account name, number of posts, followers, subscriptions, as well as the first ten user posts with likes count, comments and etc. The pyInstagram library allows sending such requests.

SQL schema
Data will be collected into thee Clickhouse tables: users, posts, comments. The users table will contain user data, such as user id, username, user’s first and last name, account description, number of followers, subscriptions, posts, comments, and likes, whether an account is verified or not, and so on.

CREATE TABLE instagram.users
    `added_at` DateTime,
    `user_id` UInt64,
    `user_name` String,
    `full_name` String,
    `base_url` String,
    `biography` String,
    `followers_count` UInt64,
    `follows_count` UInt64,
    `media_count` UInt64,
    `total_comments` UInt64,
    `total_likes` UInt64,
    `is_verified` UInt8,
    `country_block` UInt8,
    `profile_pic_url` Nullable(String),
    `profile_pic_url_hd` Nullable(String),
    `fb_page` Nullable(String)
ENGINE = ReplacingMergeTree
ORDER BY added_at

The posts table will be populated with the post owner name, post id, caption, comments coun, and so on. To check whether a post is an advertisement, Instagram carousel, or a video we can use these fields: is_ad, is_album and is_video.

CREATE TABLE instagram.posts
    `added_at` DateTime,
    `owner` String,
    `post_id` UInt64,
    `caption` Nullable(String),
    `code` String,
    `comments_count` UInt64,
    `comments_disabled` UInt8,
    `created_at` DateTime,
    `display_url` String,
    `is_ad` UInt8,
    `is_album` UInt8,
    `is_video` UInt8,
    `likes_count` UInt64,
    `location` Nullable(String),
    `recources` Array(String),
    `video_url` Nullable(String)
ENGINE = ReplacingMergeTree
ORDER BY added_at

In the comments table, we store each comment separately with the comment owner and text.

CREATE TABLE instagram.comments
    `added_at` DateTime,
    `comment_id` UInt64,
    `post_id` UInt64,
    `comment_owner` String,
    `comment_text` String
ENGINE = ReplacingMergeTree
ORDER BY added_at

Writing the script
Import the following classes from the library: Account, Media, WebAgent and Comment.

from instagram import Account, Media, WebAgent, Comment
from datetime import datetime
from clickhouse_driver import Client
import requests
import pandas as pd

Next, create an instance of the WebAgent class required for some library methods and data updating. To collect any meaningful information we need to have at least account names. Since we don’t have them yet, send the following request to search for porifles by the  keywords specified in queries_list. The search results will be composed of Instagram pages that match any keyword in the list.

agent = WebAgent()
queries_list = ['machine learning', 'data science', 'data analytics', 'analytics', 'business intelligence',
                'data engineering', 'computer science', 'big data', 'artificial intelligence',
                'deep learning', 'data scientist','machine learning engineer', 'data engineer']
client = Client(host='', user='default', password='', port='9000', database='instagram')
url = 'https://www.instagram.com/web/search/topsearch/?context=user&count=0'

Let’s iterate the keywords collecting all matching accounts. Then remove duplicates from the obtained list by converting it to set and back.

response_list = []
for query in queries_list:
    response = requests.get(url, params={
        'query': query
instagram_pages_list = []
for item in response_list:
instagram_pages_list = list(set(instagram_pages_list))

Now we need to loop through the list of pages and request detailed information about an account if it’s not in the table yet. Create an instance of the Account class and pass username as a parameter.
Then update the account information using the agent.update()
method. We will collect only the first 100 posts to keep it moving. Next, create a list named media_list to store received post ids after calling the agent.get_media() method.

Collecting user media data

all_posts_list = []
username_count = 0
for username in instagram_pages_list:
    if client.execute(f"SELECT count(1) FROM users WHERE user_name='{username}'")[0][0] == 0:
        print('username:', username_count, '/', len(instagram_pages_list))
        username_count += 1
        account_total_likes = 0
        account_total_comments = 0
            account = Account(username)
        except Exception as E:
        except Exception as E:
        if account.media_count < 100:
            post_count = account.media_count
            post_count = 100
        print(account, post_count)
        media_list, _ = agent.get_media(account, count=post_count, delay=1)
        count = 0

Because we need to count the total number of likes and comments before adding a new user to our database, we’ll start with them first. Almost all required fields belong to the Media class:

Collecting user posts

for media_code in media_list:
            if client.execute(f"SELECT count(1) FROM posts WHERE code='{media_code}'")[0][0] == 0:
                print('posts:', count, '/', len(media_list))
                count += 1

                post_insert_list = []
                post = Media(media_code)
                post_insert_list.append(datetime.now().strftime('%Y-%m-%d %H:%M:%S'))
                if post.caption is not None:
                    post_insert_list.append(post.caption.replace("'","").replace('"', ''))
                post_insert_list.append(datetime.fromtimestamp(post.date).strftime('%Y-%m-%d %H:%M:%S'))
                except TypeError:
                    post_insert_list.append('cast(Null as Nullable(UInt8))')
                if post.location is not None:
                if post.video_url is not None:
                account_total_likes += post.likes_count
                account_total_comments += post.comments_count
                        INSERT INTO posts VALUES {tuple(post_insert_list)}
                except Exception as E:

Store comments in the variable with the same name after calling the get_comments() method:

Collecting post comments

comments = agent.get_comments(media=post)
                for comment_id in comments[0]:
                    comment_insert_list = []
                    comment = Comment(comment_id)
                    comment_insert_list.append(datetime.now().strftime('%Y-%m-%d %H:%M:%S'))
                    comment_insert_list.append(comment.text.replace("'","").replace('"', ''))
                            INSERT INTO comments VALUES {tuple(comment_insert_list)}
                    except Exception as E:

And now, when we have obtained user posts and comments new information can be added to the table.

Collecting user data

user_insert_list = []
        user_insert_list.append(datetime.now().strftime('%Y-%m-%d %H:%M:%S'))
        if account.fb_page is not None:
                INSERT INTO users VALUES {tuple(user_insert_list)}
        except Exception as E:

To sum up, we have collected data of 500 users, with nearly 20K posts and 40K comments. As the database will be updated, we can write a simple query to get the top 10 ML, AI & Data Science related most followed accounts for today.

FROM users
ORDER BY followers_count DESC

And as a bonus, here is a list of the most interesting Instagram accounts on this topic:

  1. @ai_machine_learning
  2. @neuralnine
  3. @datascienceinfo
  4. @compscistuff
  5. @computersciencelife
  6. @welcome.ai
  7. @papa_programmer
  8. @data_science_learn
  9. @neuralnet.ai
  10. @techno_thinkers

View the code on GitHub

 No comments    235   10 mon   Analytics engineering   clickhouse   data analytics   instagram   python

Pandas Profiling in action: reviewing a new EDA library on Superstore Sales dataset

Estimated read time – 6 min

Before moving directly to data analysis we need to understand what type of data we are going to work with. In today’s material, we will take a closer look at the SuperStore Sales dataset, specifically at the Orders column. It includes customer shopping data of a Canadian online supermarket, such as order, product and customer ids, type of shipping, prices, product categories, names and etc. You can find more information about this dataset on GitHub. After creating a pandas DataFrame we can simply use the describe() method to get a sense of our data.

import pandas as pd

df = pd.read_csv('superstore_sales_orders.csv', decimal=',')

And oftentimes it leads to such a mess:


The source code of this library is available on GitHub

If we spend some time trying to get a grasp of this descriptive table, we can find out that customers are more likely to choose “Regular air” as a shipping type or that the majority of orders were made from Ontario. Nevertheless, there is a better tool to describe the dataset in more detail  – the pandas-profiling library. Just pass a DataFrame to it and we will get a generated HTML page with a detailed description of our dataset:

import pandas_profiling
profile = pandas_profiling.ProfileReport(df)


As you see, it returned a page with 6 sections, namely: overview, variables, interactions and correlations, number of missing values, and dataset samples.

View a full version of the Pandas Profiling Report

Data overview

Let’s move to the first subsection called “Overview”. Pandas Profiling provided the following stats: number of variables, number of observations, missing cells, duplicates, and file size. The  Variable types column shows that our DataFrame consists of 12 categorical and 9 numerical variables.


The  “Reproduction” subsection stores technical information, showing how long it took to analyze the dataset, currently installed version , configuration info and etc.


The  “Warnings” subsection informs about possible issues in the dataset structure. Now, it warns us that the “Order Date” column has too many distinct values.



Moving further, this subsection contains a detailed description of each variable, displaying the number of duplicates and missing values stored, memory size, maximum and minimal values. Right next to the stats you can see the distribution of column values.


Clicking on  Toggle details you will see more expanded information: quartiles, median and other useful descriptive statistical indicators. The remaining tabs contain a histogram displayed on the main screen, top 10 frequent values and extremes.



This section displays how variables are interconnected on a hexbin plot: The graph looks not very obvious and clear, since the legend is lacking.



The section represents correlations between variables calculated in a variety of ways. For example, the first tab shows Pearson’s r-value. It is noticeable that Profit is positively correlated with Sales. You can get a detailed explanation to each coefficient by clicking on the Toggle correlation descriptions button.


Missing values

This section includes a bar chart, matrix, and dendrogram with the number of fields in each variable. For instance, the  Product Base Margin column is missing three values.



And the final section show the first and last 10 rows as chunks of a dataset, pretty similar to the  head() method in Pandas.


Key Takeaways

The library is definitely more focused on statistics than Pandas, one can get useful descriptive stats for each variable and see their correlation. It provides a comprehensive report on a dataset in a user-friendly way, allowing to undertake an initial investigation and get a sense of data.
Still, the library has its shortfalls. If your dataset is fairly large the report generation time may be extended up to several hours. It’s a great tool for automating EDA tasks, however, it can’t do all the work for you and some details may be overlooked. If you are just getting started with data analysis, we would highly recommend to start it with pandas. It will solidify your knowledge and boost confidence in working with data.

 No comments    41   10 mon   BI-tools   pandas   pandas-profiling   python   visualisation

VIsualizing COVID-19 in Russia with Plotly

Estimated read time – 9 min

Maps are widely used in data visualization, it’s a great tool to display statistics for certain areas, regions, and cities. Before displaying the map we need to encode each region or any other administrative unit. Choropleth map gets divided into polygons and multipolygons with latitude and longitude coordinates. Plotly has a built-in solution for plotting choropleth map for America and Europe regions, however, Russia is not included yet. So we decided to use an existing GeoJSON file to map administrative regions of Russia and display the latest COVID-19 stats with Plotly.

from urllib.request import urlopen
import json
import requests
import pandas as pd
from selenium import webdriver
from bs4 import BeautifulSoup as bs
import plotly.graph_objects as go

Modifying GeoJSON

First, we need to download a public GeoJSON file with the boundaries for the Federal subjects of Russia. The file already contains some information, such as region names, but it’s still doesn’t fit the required format and missing region identifiers.

with urlopen('https://raw.githubusercontent.com/codeforamerica/click_that_hood/master/public/data/russia.geojson') as response:
    counties = json.load(response)

Besides that, there are slight differences in the namings. For example, Bashkortostan on стопкоронавирус.рф, the site we are going to scrape data from, it’s listed as “The Republic of Bashkortostan”, while in our GeoJSON file it’s simply named “Bashkortostan”. These differences should be eliminated to avoid possible confusion. Also, the names should start with a capital.

regions_republic_1 = ['Бурятия', 'Тыва', 'Адыгея', 'Татарстан', 'Марий Эл',
                      'Чувашия', 'Северная Осетия – Алания', 'Алтай',
                      'Дагестан', 'Ингушетия', 'Башкортостан']
regions_republic_2 = ['Удмуртская республика', 'Кабардино-Балкарская республика',
                      'Карачаево-Черкесская республика', 'Чеченская республика']
for k in range(len(counties['features'])):
    counties['features'][k]['id'] = k
    if counties['features'][k]['properties']['name'] in regions_republic_1:
        counties['features'][k]['properties']['name'] = 'Республика ' + counties['features'][k]['properties']['name']
    elif counties['features'][k]['properties']['name'] == 'Ханты-Мансийский автономный округ - Югра':
        counties['features'][k]['properties']['name'] = 'Ханты-Мансийский АО'
    elif counties['features'][k]['properties']['name'] in regions_republic_2:
        counties['features'][k]['properties']['name'] = counties['features'][k]['properties']['name'].title()

It’s time to create a DataFrame from the resulting GeoJSON file with the regions of Russia, we’ll take the identifiers and names.

region_id_list = []
regions_list = []
for k in range(len(counties['features'])):
df_regions = pd.DataFrame()
df_regions['region_id'] = region_id_list
df_regions['region_name'] = regions_list

As a result, our DataFrame looks like the following:

Data Scraping

We need to scrape the data stored in this table:

Let’s use the Selenium library for this task. We need to navigate to the webpage and convert it into a BeautifulSoup object

driver = webdriver.Chrome()
source_data = driver.page_source
soup = bs(source_data, 'lxml')

The region names are wrapped with <th> tags, while the latest data is stored in table cells, each one is defined with a <td> tag.

divs_data = soup.find_all('td')

The divs_data list should return something like this:

The data is grouped in one line, this includes both new cases and active ones. It is noticeable that each region corresponds to five values, for Moscow these are the first five, for Moscow Region the next five and so on. We can use this pattern to create five lists and populate with values according to the index. The first value will be appended to the list with active cases, the second value to the list of new ones, etc. After every five values, the index will be reset to zero.

count = 1
for td in divs_data:
    if count == 1:
    elif count == 2:
    elif count == 3:
    elif count == 4:
    elif count == 5:
        count = 0
    count += 1

The next step is to extract the region names from the table, they are stored within the col-region class. We also need to clean up the data by eliminating extra white spaces and line breaks.

divs_region_names = soup.find_all('th', {'class':'col-region'})
region_names_list = []
for i in range(1, len(divs_region_names)):
    region_name = divs_region_names[i].text
    region_name = region_name.replace('\n', '').replace('  ', '')

Create a DataFrame:

df = pd.DataFrame()
df['region_name'] = region_names_list
df['sick'] = sick_list
df['new'] = new_list
df['cases'] = cases_list
df['healed'] = healed_list
df['died'] = died_list

After reviewing our data once again we detected white space under the index 10. This should be fixed immediately, otherwise, we may run into problems.

df.loc[10, 'region_name'] = df[df.region_name == 'Челябинская область '].region_name.item().strip(' ')

Finally, we can merge our DataFrame on the region_name column, so that the resulted table will include a column with region id, which is required to make a choropleth map.

df = df.merge(df_regions, on='region_name')

Creating a choropleth map with Plotly

Let’s create a new figure and pass a choroplethmapbox object to it. The geojson parameter will accept the counties variable with the GeoJSON file, assign the region_id to locations. The z parameter represents the data to be color-coded, in this example we’re passing the number of new cases for each region. Assign the region names to text. The colorscale parameter accepts lists with values ranging from 0 to 1 and RGB color codes. Here, the palette changes from green to yellow and then red, depending on the number of active cases. By passing the values stored in customdata we can change our hovertemplate.

fig = go.Figure(go.Choroplethmapbox(geojson=counties,
                           colorscale=[[0, 'rgb(34, 150, 79)'],
                                       [0.2, 'rgb(249, 247, 174)'],
                                       [0.8, 'rgb(253, 172, 99)'],
                                       [1, 'rgb(212, 50, 44)']],
                           customdata=np.stack([df['cases'], df['died'], df['sick'], df['healed']], axis=-1),
                           hovertemplate='<b>%{text}</b>'+ '<br>' +
                                         'New cases: %{z}' + '<br>' +
                                         'Active cases: %{customdata[0]}' + '<br>' +
                                         'Deaths: %{customdata[1]}' + '<br>' +
                                         'Total cases: %{customdata[2]}' + '<br>' +
                                         'Recovered: %{customdata[3]}' +
                           hoverinfo='text, z'))

Let’s customize the map, we will use a ready-to-go neutral template, called carto-positron. Set the parameters and display the map:
mapbox_zoom: responsible for zooming;
mapbox_center: centers the map;
marker_line_width: border width (we removed the borders by setting this parameter to 0);
margin: usually accepts 0 values to make the map wider.

                  mapbox_zoom=1, mapbox_center = {"lat": 66, "lon": 94})

And here is our map. According to the plot, we can say that the highest number of cases per day is happening in Moscow – 608 new cases. It’s really high compared to the other regions, and especially to Nenets Autonomous Okrug, where this number is surprisingly low.

View the code on GitHub

 No comments    1016   11 mon   dash   data analytics   plotly   python
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