Table of Contents
Pandas plot allows users to set an index for the plot, which can be used to access and modify the plot data. To use an index, the index must be set before the plot is created. This can be done by setting the index when creating the DataFrame object or by using the set_index() method to set the index for an existing DataFrame. Examples of how to use an index to access and modify the plot data include using the set_index() and reset_index() methods, accessing the plot data using .loc[] and .iloc[], and using the .index attribute.
You can use one of the following methods to use the values in the index of a pandas DataFrame as the x-axis values in a plot:
Method 1: Use plot()
df.plot(y='my_column')
If you don’t specify a variable to use for the x-axis then pandas will use the index values by default.
Method 2: Use plot() with use_index=True
df.plot(y='my_column', use_index=True)
The use_index=True argument explicitly tells pandas to use the index values for the x-axis.
Both of these methods will produce the same result.
The following examples show how to use each method in practice with the following pandas DataFrame:
import pandas as pd #create DatFrame df = pd.DataFrame({'sales': [8, 8, 9, 12, 13, 14, 22, 26, 25, 22]}, index=pd.date_range('1/1/2020', periods=10, freq='m')) #view DataFrame print(df) sales 2020-01-31 8 2020-02-29 8 2020-03-31 9 2020-04-30 12 2020-05-31 13 2020-06-30 14 2020-07-31 22 2020-08-31 26 2020-09-30 25 2020-10-31 22
Example 1: Use plot()
The following code shows how to use the plot() function in pandas to create a line chart that uses the index values in the DataFrame as the x-axis and the values in the sales column as the y-axis values:
#create line chart and use index values as x-axis values df.plot(y='sales')
Notice that the plot automatically uses the dates in the index of the DataFrame as the values on the x-axis of the line chart.
Since we didn’t specify a variable to use on the x-axis, pandas used the index values by default.
Example 2: Use plot() with use_index=True
#create line chart and use index values as x-axis values df.plot(y='sales', use_index=True)
Once again the plot uses the dates in the index of the DataFrame as the values on the x-axis of the line chart.
Notice that this chart matches the previous chart.