Multiple x labels on Pyplot

问题

Below is my code for a line graph. I would like another x label under the current one (so I can show the days of the week).

import matplotlib.pyplot as plt
import pandas as pd
import seaborn as sns;sns.set()

sns.set()

data = pd.read_csv("123.csv")

data['DAY']=["01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31"]

plt.figure(figsize=(15,8))  
plt.plot('DAY','SWST',data=data,linewidth=2,color="k")
plt.plot('DAY','WMID',data=data,linewidth=2,color="m")

plt.xlabel('DAY', fontsize=20)
plt.ylabel('VOLUME', fontsize=20)
plt.legend()

EDIT: After following the documentation, I have 2 issues. The scale has changed from 31 to 16, and the days of the week do not line up with the day number.

data['DAY']=["01","02","03","04","05","06","07","08","09","10","11","12","13","14","15","16","17","18","19","20","21","22","23","24","25","26","27","28","29","30","31"]

tick_labels=['1','\n\nThu','2','\n\nFri','3','\n\nSat','4','\n\nSun','5','\n\nMon','6','\n\nTue','7','\n\nWed','8','\n\nThu','9','\n\nFri','10','\n\nSat','11','\n\nSun','12','\n\nMon','13','\n\nTue','14','\n\nWed','15','\n\nThu','16','\n\nFri','17','\n\nSat','18','\n\nSun','19','\n\nMon','20','\n\nTue','21','\n\nWed','22','\n\nThu','23','\n\nFri','24','\n\nSat','25','\n\nSun','26','\n\nMon','27','\n\nTue','28','\n\nWed','29','\n\nThu','30','\n\nFri','31','\n\nSat']
tick_locations = np.arange(31)

plt.figure(figsize=(15,8))

plt.xticks(tick_locations, tick_labels)
plt.plot('DAY','SWST',data=data,linewidth=2,color="k")
plt.plot('DAY','WMID',data=data,linewidth=2,color="m")     

plt.xlabel('DAY', fontsize=20)
plt.ylabel('VOLUME', fontsize=20)
plt.legend()

plt.show()

回答1:

The pyplot function you are looking for is plt.xticks(). This is essentially a combination of ax.set_xticks() and ax.set_xticklabels()

From the documentation:

Parameters:

ticks : array_like

A list of positions at which ticks should be placed. You can pass an empty list to disable xticks.

labels:

array_like, optional A list of explicit labels to place at the given locs.

You would want something like the below code. Note you should probably explicitly set the tick locations as well as the labels to avoid setting labels in the wrong positions:

tick_labels = ['1','\n\nThu','2',..., '31','\n\nSat')
plt.xticks(tick_locations, tick_labels)

Note that the object-orientated API (i.e. using ax.) allows for more customisable plots.

Update

After the edit, I see that the labels you want to go below are part of the same list. Therefore your label list actually has a length of 62. So you need to join every 2 elements of your list together:

tick_labels=['1','\n\nThu','2','\n\nFri','3','\n\nSat','4','\n\nSun','5','\n\nMon','6','\n\nTue','7','\n\nWed','8',
             '\n\nThu','9','\n\nFri','10','\n\nSat','11','\n\nSun','12','\n\nMon','13','\n\nTue','14','\n\nWed','15',
             '\n\nThu','16','\n\nFri','17','\n\nSat','18','\n\nSun','19','\n\nMon','20','\n\nTue','21','\n\nWed','22',
             '\n\nThu','23','\n\nFri','24','\n\nSat','25','\n\nSun','26','\n\nMon','27','\n\nTue','28','\n\nWed','29',
             '\n\nThu','30','\n\nFri','31','\n\nSat']

tick_locations = np.arange(31)

new_labels = [ ''.join(x) for x in zip(tick_labels[0::2], tick_labels[1::2]) ]
plt.figure(figsize=(15, 8))

plt.xticks(tick_locations, new_labels)

plt.show()

回答2:

Never use ax.set_xticklabels without setting the locations of the ticks as well. This can be done via ax.set_xticks.

ax.set_xticks(...)
ax.set_xticklabels(...)

Of course you may do the same with pyplot

ax = plt.gca()
ax.set_xticks(...)
ax.set_xticklabels(...)

来源：https://stackoverflow.com/questions/53043732/multiple-x-labels-on-pyplot

标签

python

matplotlib

seaborn