import pandas as pd

import numpy as np
import matplotlib.pyplot as plt

df = pd.DataFrame({

    'color': ['red','red','red','blue','blue','blue'],

    'x': [0,1,2,3,4,5],'y': [0,1,2,9,16,25]

})

fig, ax = plt.subplots()

for key, group in df.groupby(['color']):

    ax = group(ax=ax, kind='line', x='x', y='y', c=key, label=key)

plt.legend()

plt.show()

ax = None

for key, group in df.groupby(['color']):

    ax = group(ax=ax, kind='line', x='x', y='y', c=key, label=key)

plt.legend()

plt.show()

df_r = df[df["color"] == "red"]

df_b = df[df["color"] == "blue"]

plt.title('混合图')  #标题

plt.plot(df_r.x, df_r.y, color='red', label='red')

plt.plot(df_b.x, df_b.y, color='blue', label='blue')

plt.legend()  #显示上面的label

plt.xlabel('index')

plt.ylabel('count')

plt.show()