Matplotlib-使用for循环绘制分组值

Question

我正在尝试使用for循环绘制按列值分组的图形，而不知道该列中唯一值的数量。

您可以在下面看到示例代码（无for循环）和所需的输出。

我希望每个地块都有不同的颜色和标记（如下所示）。

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这是代码：

import pandas as pd
from numpy import random

df = pd.DataFrame(data = random.randn(5,4), index = ['A','B','C','D','E'],
columns = ['W','X','Y','Z'])

df['W'] = ['10/01/2018 12:00:00','10/03/2018 13:00:00',
           '10/03/2018 12:30:00','10/04/2018 12:05:00',
           '10/08/2018 12:00:15']

df['W']=pd.to_datetime(df['W'])

df['Entity'] = ['C201','C201','C201','C202','C202']

print(df.head()) 

fig, ax = plt.subplots()
df[df['Entity']=="C201"].plot(x="W",y="Y",label='C201',ax=ax,marker='x')
df[df['Entity']=="C202"].plot(x="W",y="Y",label='C202',ax=ax, marker='o')

这是输出：

Answer 1

您可以先找出df['Entity']的唯一值，然后在它们上循环。要为每个实体自动生成新标记，您可以定义一些标记的顺序（在下面的答案中为5），该顺序将通过marker=next(marker)重复。

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完成最小答案

import itertools
import pandas as pd
from numpy import random
import matplotlib.pyplot as plt

marker = itertools.cycle(('+', 'o', '*', '^', 's')) 
df = pd.DataFrame(data = random.randn(5,4), index = ['A','B','C','D','E'],
columns = ['W','X','Y','Z'])

df['W'] = ['10/01/2018 12:00:00','10/03/2018 13:00:00',
           '10/03/2018 12:30:00','10/04/2018 12:05:00',
           '10/08/2018 12:00:15']

df['W']=pd.to_datetime(df['W'])

df['Entity'] = ['C201','C201','C201','C202','C202']

fig, ax = plt.subplots()

for idy in np.unique(df['Entity'].values):
    df[df['Entity']==idy].plot(x="W",y="Y", label=idy, ax=ax, marker=next(marker))

plt.legend()
plt.show()