Set Xticks frequency to dataframe index

问题

I currently have a dataframe that has as an index the years from 1990 to 2014 (25 rows). I want my plot to have the X axis with all the years showing. I'm using add_subplot as I plan to have 4 plots in this figure (all of them with the same X axis).

To create the dataframe:

import pandas as pd
import numpy as np

index = np.arange(1990,2015,1)
columns = ['Total Population','Urban Population']

pop_plot = pd.DataFrame(index=index, columns=columns)
pop_plot = df_.fillna(0)

pop_plot['Total Population'] = np.arange(150,175,1)
pop_plot['Urban Population'] = np.arange(50,125,3)

The code that I currently have:

fig = plt.figure(figsize=(10,5))
ax1 = fig.add_subplot(2,2,1, xticklabels=pop_plot.index)
plt.subplot(2, 2, 1)

plt.plot(pop_plot)
legend = plt.legend(pop_plot, bbox_to_anchor=(0.1, 1, 0.8, .45), loc=3, ncol=1, mode='expand')
legend.get_frame().set_alpha(0)

ax1.set_xticks(range(len(pop_plot.index)))

This is the plot that I get:

When I comment the set_xticks I get the following plot:

#ax1.set_xticks(range(len(pop_plot.index)))

I've tried a couple of answers that I found here, but I didn't have much success.

Thanks in advance.

回答1:

It's not clear what ax1.set_xticks(range(len(pop_plot.index))) should be used for. It will set the ticks to the numbers 0,1,2,3 etc. while your plot should range from 1990 to 2014.

Instead, you want to set the ticks to the numbers of your data:

ax1.set_xticks(pop_plot.index)

Complete corrected example:

import matplotlib.pyplot as plt
import pandas as pd
import numpy as np

index = np.arange(1990,2015,1)
columns = ['Total Population','Urban Population']

pop_plot = pd.DataFrame(index=index, columns=columns)

pop_plot['Total Population'] = np.arange(150,175,1)
pop_plot['Urban Population'] = np.arange(50,125,3)


fig = plt.figure(figsize=(10,5))
ax1 = fig.add_subplot(2,2,1)

ax1.plot(pop_plot)
legend = ax1.legend(pop_plot, bbox_to_anchor=(0.1, 1, 0.8, .45), loc=3, ncol=1, mode='expand')
legend.get_frame().set_alpha(0)

ax1.set_xticks(pop_plot.index)
plt.show()

来源：https://stackoverflow.com/questions/46755563/set-xticks-frequency-to-dataframe-index