Plotting Pandas DataFrame from pivot

I am trying to plot a line graph comparing the Murder Rates of particular States through the years 1960-1962 using Pandas in a Jupyter Notebook.

A little context about where I am now, and how I arrived here:

I’m using a crime csv file, which looks like this:

I’m only interested in 3 columns for the time being: State, Year, and Murder Rate. Specifically I was interested in only 5 states – Alaska, Michigan, Minnesota, Maine, Wisconsin.

So to produce the desired table, I did this (only showing top 5 row entries):

al_mi_mn_me_wi = crimes[(crimes['State'] == 'Alaska') | (crimes['State'] =='Michigan') | (crimes['State'] =='Minnesota') | (crimes['State'] =='Maine') | (crimes['State'] =='Wisconsin')]
control_df = al_mi_mn_me_wi[['State', 'Year', 'Murder Rate']]

From here I used the pivot function

df = control_1960_to_1962.pivot(index = 'Year', columns = 'State',values= 'Murder Rate' ) 

And this is where I get stuck. I received KeyError when doing (KeyError was Year):

df.plot(x='Year', y='Murder Rate', kind='line')

and when attempting just

df.plot()

I get this wonky graph.

How do I get my desired graph?

Answer

Given a dataframe in a long (tidy) format, pandas.DataFrame.pivot is used to transform to a wide format, which can be plotted directly with pandas.DataFrame.plot

Tested in python 3.8.11, pandas 1.3.3, matplotlib 3.4.3

import numpy as np
import pandas as pd

control_1960_to_1962 = pd.DataFrame({
    'State': np.repeat(['Alaska', 'Maine', 'Michigan', 'Minnesota', 'Wisconsin'], 3),
    'Year': [1960, 1961, 1962]*5,
    'Murder Rate': [10.2, 11.5, 4.5, 1.7, 1.6, 1.4, 4.5, 4.1, 3.4, 1.2, 1.0, .9, 1.3, 1.6, .9]
})

df = control_1960_to_1962.pivot(index='Year', columns='State', values='Murder Rate')

# display(df)
State  Alaska  Maine  Michigan  Minnesota  Wisconsin
Year                                                
1960     10.2    1.7       4.5        1.2        1.3
1961     11.5    1.6       4.1        1.0        1.6
1962      4.5    1.4       3.4        0.9        0.9

The plots

You can tell Pandas (and through it the matplotlib package that actually does the plotting) what xticks you want explicitly:

ax = df.plot(xticks=df.index, ylabel='Murder Rate')

Output:

ax is a matplotlib.axes.Axes object, and there are many, many customizations you can make to your plot through it.

Here’s how to plot with the States on the x axis:

ax = df.T.plot(kind='bar', ylabel='Murder Rate')

Output: