我需要帮助从 dataframe 绘制条形图

Question

I have the following dataframe:

    AQI         Year     City
0   349.407407  2015    'Patna'
1   297.024658  2015    'Delhi'
2   283.007605  2015    'Ahmedabad'
3   297.619178  2016    'Delhi'
4   282.717949  2016    'Ahmedabad'
5   250.528701  2016    'Patna'
6   379.753623  2017    'Ahmedabad'
7   325.652778  2017    'Patna'
8   281.401216  2017    'Gurugram'
9   443.053221  2018    'Ahmedabad'
10  248.367123  2018    'Delhi'
11  233.772603  2018    'Lucknow'
12  412.781250  2019    'Ahmedabad'
13  230.720548  2019    'Delhi'
14  217.626741  2019    'Patna'
15  214.681818  2020    'Ahmedabad'
16  181.672131  2020    'Delhi'
17  162.251366  2020    'Patna'

I would like to group data for each year, ie 2015, 2016, 2017 2018...2020 on the x axis, with AQI on the y axis. I am a newbie and please excuse the lack of depth in my question.

Answer 1

You can "pivot" your data to support your desired plotting output. Here we set the rows as Year , columns as City , and values as AQI .

pivot = pd.pivot_table(
    data=df,
    index='Year',
    columns='City',
    values='AQI',
)

Year	Ahmedabad	Delhi	Gurugram	Lucknow	Patna
2015	283.007605	297.024658	NaN	NaN	349.407407
2016	282.717949	297.619178	NaN	NaN	250.528701
2017	379.753623	NaN	281.401216	NaN	325.652778
2018	443.053221	248.367123	NaN	233.772603	NaN
2019	412.781250	230.720548	NaN	NaN	217.626741
2020	214.681818	181.672131	NaN	NaN	162.251366

Then you can plot this pivot table directly:

pivot.plot.bar(xlabel='Year', ylabel='AQI')

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Old answer

Are you looking for the mean AQI per year? If so, you can do some pandas chaining, assuming your data is in a DataFrame df :

df.groupby('Year').mean().plot.bar(xlabel='Year', ylabel='AQI')