Exercise: Trellis Chart, Column Chart, and Stacked Column Chart

import pandas as pd
df = pd.read_csv('data/average_internet_speed.csv',parse_dates=['quarter'])
print(df)

import pandas as pd
import altair as alt
import os
df = pd.read_csv('data/average_internet_speed.csv',parse_dates=['quarter'])
# drop countries for which there is only just one value
df = df[ ~ df['Country'].isin(['MDA', 'BIH','XKO', 'UA'])]
# select all countries
countries = df.Country.unique()
# split the chart in a 4 x 10 grid
start = 0
burst = 10
end = burst
charts = []
# for each row, draw a line chart
# store all the charts in a list
for i in range(4):
    
    # select only the current countries
    df_part = df[df['Country'].isin(countries[start:end])]
    # TRELLIS CHART
    # use mark_line() to draw the chart
    # COLUMN CHART
    # use mark_bark to draw the chart
    #chart = 
    
    #charts.append(chart)
    start = end
    end = start + burst
# uncomment the following lines to show the chart   
#charts1 = charts[0] & charts[1]
#charts2 = charts[2] & charts[3]
#(charts1 & charts2).save('chart.html')
#os.system('cat chart.html')

import pandas as pd
import altair as alt
import os
df = pd.read_csv('data/average_internet_speed.csv',parse_dates=['quarter'])
# drop countries for which there is only just one value
df = df[ ~ df['Country'].isin(['MDA', 'BIH','XKO', 'UA'])]
countries = df.Country.unique()
# draw a drop down menu to select a specific country
input_dropdown = alt.binding_select(options=countries, name='Country ')
selection = alt.selection_single(fields=['Country'], bind=input_dropdown, empty='none')
color = alt.condition(selection,
                    'Country',
                    alt.value('lightgray'))
# draw the chart using mark_bar()
# use add_selection(selection) to connect the selection to the chart
# chart = alt.Chart(df)
# uncomment the following lines to show the chart
#chart.save('chart.html')
#os.system('cat chart.html')