问题
<table class="table table-bordered table-hover table-condensed">
<thead><tr><th title="Field #1">year</th>
<th title="Field #2">primary_type</th>
<th title="Field #3">Number_of_Incidents</th>
<th title="Field #4">number_of_arrests</th>
<th title="Field #5">percent_arrest</th>
<th title="Field #6">rank</th>
</tr></thead>
<tbody><tr>
<td align="right">2018</td>
<td>THEFT</td>
<td align="right">57330</td>
<td align="right">5503</td>
<td align="right">9.6</td>
<td align="right">1</td>
</tr>
<tr>
<td align="right">2018</td>
<td>BATTERY</td>
<td align="right">44667</td>
<td align="right">8886</td>
<td align="right">19.89</td>
<td align="right">2</td>
</tr>
<tr>
<td align="right">2018</td>
<td>CRIMINAL DAMAGE</td>
<td align="right">24889</td>
<td align="right">1498</td>
<td align="right">6.02</td>
<td align="right">3</td>
</tr>
<tr>
<td align="right">2018</td>
<td>ASSAULT</td>
<td align="right">18229</td>
<td align="right">2931</td>
<td align="right">16.08</td>
<td align="right">4</td>
</tr>
<tr>
<td align="right">2018</td>
<td>DECEPTIVE PRACTICE</td>
<td align="right">15879</td>
<td align="right">713</td>
<td align="right">4.49</td>
<td align="right">5</td>
</tr>
<tr>
<td align="right">2017</td>
<td>THEFT</td>
<td align="right">64334</td>
<td align="right">6459</td>
<td align="right">10.04</td>
<td align="right">1</td>
</tr>
<tr>
<td align="right">2017</td>
<td>BATTERY</td>
<td align="right">49213</td>
<td align="right">10060</td>
<td align="right">20.44</td>
<td align="right">2</td>
</tr>
<tr>
<td align="right">2017</td>
<td>CRIMINAL DAMAGE</td>
<td align="right">29040</td>
<td align="right">1747</td>
<td align="right">6.02</td>
<td align="right">3</td>
</tr>
<tr>
<td align="right">2017</td>
<td>ASSAULT</td>
<td align="right">19298</td>
<td align="right">3455</td>
<td align="right">17.9</td>
<td align="right">4</td>
</tr>
<tr>
<td align="right">2017</td>
<td>DECEPTIVE PRACTICE</td>
<td align="right">18816</td>
<td align="right">805</td>
<td align="right">4.28</td>
<td align="right">5</td>
</tr>
<tr>
<td align="right">2016</td>
<td>THEFT</td>
<td align="right">61600</td>
<td align="right">6518</td>
<td align="right">10.58</td>
<td align="right">1</td>
</tr>
<tr>
<td align="right">2016</td>
<td>BATTERY</td>
<td align="right">50292</td>
<td align="right">10328</td>
<td align="right">20.54</td>
<td align="right">2</td>
</tr>
<tr>
<td align="right">2016</td>
<td>CRIMINAL DAMAGE</td>
<td align="right">31018</td>
<td align="right">1668</td>
<td align="right">5.38</td>
<td align="right">3</td>
</tr>
<tr>
<td align="right">2016</td>
<td>ASSAULT</td>
<td align="right">18738</td>
<td align="right">3490</td>
<td align="right">18.63</td>
<td align="right">4</td>
</tr>
<tr>
<td align="right">2016</td>
<td>DECEPTIVE PRACTICE</td>
<td align="right">18733</td>
<td align="right">815</td>
<td align="right">4.35</td>
<td align="right">5</td>
</tr>
<tr>
<td align="right">2015</td>
<td>THEFT</td>
<td align="right">57335</td>
<td align="right">6771</td>
<td align="right">11.81</td>
<td align="right">1</td>
</tr>
<tr>
<td align="right">2015</td>
<td>BATTERY</td>
<td align="right">48918</td>
<td align="right">11558</td>
<td align="right">23.63</td>
<td align="right">2</td>
</tr>
<tr>
<td align="right">2015</td>
<td>CRIMINAL DAMAGE</td>
<td align="right">28675</td>
<td align="right">1835</td>
<td align="right">6.4</td>
<td align="right">3</td>
</tr>
<tr>
<td align="right">2015</td>
<td>NARCOTICS</td>
<td align="right">23883</td>
<td align="right">23875</td>
<td align="right">99.97</td>
<td align="right">4</td>
</tr>
<tr>
<td align="right">2015</td>
<td>OTHER OFFENSE</td>
<td align="right">17552</td>
<td align="right">4795</td>
<td align="right">27.32</td>
<td align="right">5</td>
</tr>
<tr>
<td align="right">2014</td>
<td>THEFT</td>
<td align="right">61561</td>
<td align="right">7415</td>
<td align="right">12.04</td>
<td align="right">1</td>
</tr>
<tr>
<td align="right">2014</td>
<td>BATTERY</td>
<td align="right">49447</td>
<td align="right">12517</td>
<td align="right">25.31</td>
<td align="right">2</td>
</tr>
<tr>
<td align="right">2014</td>
<td>NARCOTICS</td>
<td align="right">29116</td>
<td align="right">29000</td>
<td align="right">99.6</td>
<td align="right">3</td>
</tr>
<tr>
<td align="right">2014</td>
<td>CRIMINAL DAMAGE</td>
<td align="right">27798</td>
<td align="right">2095</td>
<td align="right">7.54</td>
<td align="right">4</td>
</tr>
<tr>
<td align="right">2014</td>
<td>OTHER OFFENSE</td>
<td align="right">16979</td>
<td align="right">4159</td>
<td align="right">24.49</td>
<td align="right">5</td>
</tr>
<tr>
<td align="right">2013</td>
<td>THEFT</td>
<td align="right">71530</td>
<td align="right">7727</td>
<td align="right">10.8</td>
<td align="right">1</td>
</tr>
<tr>
<td align="right">2013</td>
<td>BATTERY</td>
<td align="right">54002</td>
<td align="right">12927</td>
<td align="right">23.94</td>
<td align="right">2</td>
</tr>
<tr>
<td align="right">2013</td>
<td>NARCOTICS</td>
<td align="right">34127</td>
<td align="right">33819</td>
<td align="right">99.1</td>
<td align="right">3</td>
</tr>
<tr>
<td align="right">2013</td>
<td>CRIMINAL DAMAGE</td>
<td align="right">30853</td>
<td align="right">2107</td>
<td align="right">6.83</td>
<td align="right">4</td>
</tr>
<tr>
<td align="right">2013</td>
<td>OTHER OFFENSE</td>
<td align="right">17993</td>
<td align="right">3400</td>
<td align="right">18.9</td>
<td align="right">5</td>
</tr>
</tbody></table>I have a unique situation. In my data I have year and within each year I have 5 categories and it's corresponding counts. I was able to create a stacked bar chart of those 5 categories for a corresponding year. However, I want to show 5 adjacent bars for each year on my x-axis. For y-axis it should show a corresponding total for each bar.
Here is my current viz and code:
import altair as alt
base = alt.Chart(q13a).encode(
alt.X('year:O',
axis=alt.Axis(format='%b', title='Year'),
scale=alt.Scale(zero=False)
),
tooltip = ['year']
)
bar = base.mark_bar().encode(
alt.Y('sum(Number_of_Incidents)',
axis=alt.Axis(title='sum(Number_of_Incidents)'))
,color=alt.Color('primary_type')
#tooltip = ['primary_type']
)
line = base.mark_line(color='red').encode(
#y='No_of_repos',
alt.Y('percent_arrest',
axis=alt.Axis(title='percent_arrest')),
)
alt.layer(
bar
).resolve_scale(
y='independent'
).properties(
height=500,
width=1200
)
My question is, instead of a stacked bar, how can I create 5 adjacent bars for each year on my x-axis ?
Thanks for your help in advance.
回答1:
The only way to do side-by-side bars is to use a column encoding alongside an x encoding. You can follow the grouped bar chart example from Altair's example gallery here: https://altair-viz.github.io/gallery/grouped_bar_chart.html
The result for your data would be something like this:
import altair as alt
import pandas as pd
import numpy as np
q13a = pd.DataFrame({
'year': np.random.randint(2000, 2018, 100),
'Number_of_Incidents': np.random.randint(0, 20, 100),
'percent_arrest': np.random.rand(100),
'primary_type': np.random.choice(['a', 'b', 'c', 'd', 'e'], 100)
})
alt.Chart(q13a).mark_bar().encode(
x=alt.X('primary_type', scale=alt.Scale(rangeStep=8), title=None),
y=alt.Y('sum(Number_of_Incidents)', title='sum(Number_of_Incidents)'),
color='primary_type',
column='year',
tooltip=['year']
).configure_view(
stroke='transparent'
)
回答2:
@jakevdp has already answered, but for the sake of answering your last question (even though you should ask several questions if you have several points), you can sort the bars with alt.EncodingSortField.
import altair as alt
alt.Chart(q13a).mark_bar().encode(
x=alt.X('primary_type:N',
scale=alt.Scale(rangeStep=8),
axis=None,
sort=alt.EncodingSortField(field='Number_of_Incident',
op='sum',
order='ascending')
),
y=alt.Y('sum(Number_of_Incidents):Q', title='sum(Number_of_Incidents)'),
color='primary_type:N',
tooltip=['primary_type:N',
'year:O',
alt.Tooltip('sum(Number_of_Incidents):Q',
title='Number of incidents')
]
).facet(
column=alt.Column('year:O',
header=alt.Header(title=None)),
).resolve_scale(
x='independent'
).configure_view(
stroke='transparent'
)
Data
import pandas as pd
from io import StringIO
q13a = pd.read_table(StringIO("""year primary_type Number_of_Incidents number_of_arrests percent_arrest rank
2018 THEFT 57330 5503 9.6 1
2018 BATTERY 44667 8886 19.89 2
2018 CRIMINAL DAMAGE 24889 1498 6.02 3
2018 ASSAULT 18229 2931 16.08 4
2018 DECEPTIVE PRACTICE 15879 713 4.49 5
2017 THEFT 64334 6459 10.04 1
2017 BATTERY 49213 10060 20.44 2
2017 CRIMINAL DAMAGE 29040 1747 6.02 3
2017 ASSAULT 19298 3455 17.9 4
2017 DECEPTIVE PRACTICE 18816 805 4.28 5
2016 THEFT 61600 6518 10.58 1
2016 BATTERY 50292 10328 20.54 2
2016 CRIMINAL DAMAGE 31018 1668 5.38 3
2016 ASSAULT 18738 3490 18.63 4
2016 DECEPTIVE PRACTICE 18733 815 4.35 5
2015 THEFT 57335 6771 11.81 1
2015 BATTERY 48918 11558 23.63 2
2015 CRIMINAL DAMAGE 28675 1835 6.4 3
2015 NARCOTICS 23883 23875 99.97 4
2015 OTHER OFFENSE 17552 4795 27.32 5
2014 THEFT 61561 7415 12.04 1
2014 BATTERY 49447 12517 25.31 2
2014 NARCOTICS 29116 29000 99.6 3
2014 CRIMINAL DAMAGE 27798 2095 7.54 4
2014 OTHER OFFENSE 16979 4159 24.49 5
2013 THEFT 71530 7727 10.8 1
2013 BATTERY 54002 12927 23.94 2
2013 NARCOTICS 34127 33819 99.1 3
2013 CRIMINAL DAMAGE 30853 2107 6.83 4
2013 OTHER OFFENSE 17993 3400 18.9 5"""))
Created on 2018-11-28 by the reprexpy package
来源：https://stackoverflow.com/questions/53517044/how-to-create-a-nested-grouped-bar-chart-using-altair-added-sample-data