python - 用均匀间隔的时间戳替换 x-ticks

Question

我正在尝试插入timestampsfor x-axisascatter plot而不是total seconds. 以下是我迄今为止尝试过的，但我error对这条线有所了解；

loc, labels = ax.set_xticks(x)

AttributeError: 'NoneType' object has no attribute 'update'

例子：

import pandas as pd
import matplotlib.pyplot as plt

d = ({
    'A' : ['08:00:00','08:10:00','08:12:00','08:26:00','08:29:00','08:31:00','10:10:00','10:25:00','10:29:00','10:31:00'],
    'B' : ['1','1','1','2','2','2','7','7','7','7'],     
    'C' : ['X','Y','Z','X','Y','Z','A','X','Y','Z'],
    })

df = pd.DataFrame(data=d)

fig,ax = plt.subplots()

x = df['A']
y = df['B']

x_numbers = (pd.to_timedelta(df['A']).dt.total_seconds())

ax.scatter(x_numbers, y)
loc, labels = ax.set_xticks(x)
newlabels = [str(pd.Timedelta(str(i)+ ' seconds')).split()[2] for i in loc]
ax.set_xticks(loc, newlabels)

注意 我需要使用ax而不是plt因为这个情节被称为subplot. 如果我使用情节，axis则将分配给最后一个subplot而不是指定的。

标签： pythonpandasmatplotlib

Answer 1

我建议直接使用日期时间而不弄乱刻度标签。使用matplotlib.dates.MinuteLocator加法可以为您提供不错的刻度位置。

import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.dates as mdates

d = ({
    'A' : ['08:00:00','08:10:00','08:12:00','08:26:00','08:29:00','08:31:00',
           '10:10:00','10:25:00','10:29:00','10:31:00'],
    'B' : ['1','1','1','2','2','2','7','7','7','7'],     
    'C' : ['X','Y','Z','X','Y','Z','A','X','Y','Z'],
    })

df = pd.DataFrame(data=d)
df['A'] = pd.to_datetime(df['A'])

fig,ax = plt.subplots()

ax.scatter(df["A"].values, df["B"].values)
ax.set_xlim(df["A"].min(), df["A"].max())

ax.xaxis.set_major_locator(mdates.MinuteLocator((0,30)))
ax.xaxis.set_major_formatter(mdates.DateFormatter("%H:%M"))
plt.show()