pandas - 散布 plot，每個點都有不同的顏色圖例

Question

從以下示例開始：

fig, ax = plt.subplots()

df = pd.DataFrame({'n1':[1,2,1,3], 'n2':[1,3,2,1], 'l':['a','b','c','d']})

for label in df['l']:

    df.plot('n1','n2', kind='scatter', ax=ax, s=50, linewidth=0.1, label=label)

我得到的是以下散點圖：

我現在正在嘗試為四個點中的每一個設置不同的顏色。 我知道我可以在列表中循環一組，例如 4 colors，例如：

colorlist = ['b','r','c','y']

但由於我的真實數據集至少包含 20 個不同的點，所以我一直在尋找一種“顏色生成器”在其中循環。

Answer 1

以下方法將創建一個與數據框一樣長的顏色列表，然后用每種顏色的標簽繪制一個點：

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

fig, ax = plt.subplots()

df = pd.DataFrame({'n1':[1,2,1,3], 'n2':[1,3,2,1], 'l':['a','b','c','d']})

colormap = cm.viridis
colorlist = [colors.rgb2hex(colormap(i)) for i in np.linspace(0, 0.9, len(df['l']))]

for i,c in enumerate(colorlist):

    x = df['n1'][i]
    y = df['n2'][i]
    l = df['l'][i]

    ax.scatter(x, y, label=l, s=50, linewidth=0.1, c=c)

ax.legend()

plt.show()

Answer 2

IIUC 你可以這樣做：

import matplotlib.pyplot as plt
from matplotlib import colors
import pandas as pd

colorlist = list(colors.ColorConverter.colors.keys())
fig, ax = plt.subplots()
[df.iloc[[i]].plot.scatter('n1', 'n2', ax=ax, s=50, label=l,
                         color=colorlist[i % len(colorlist)])
 for i,l in enumerate(df.l)]

顏色列表：

In [223]: colorlist
Out[223]: ['m', 'b', 'g', 'r', 'k', 'y', 'c', 'w']

PS colorlist[i % len(colorlist)] - 應始終保持在列表范圍內

Answer 3

這個怎么樣，

---

這是源代碼，

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

fig, ax = plt.subplots()

df = pd.DataFrame({'n1':[1,2,1,3], 'n2':[1,3,2,1], 'l':['a','b','c','d']})

#colors = ['b','r','c','y']
nrof_labels = len(df['l'])
colors = cm.rainbow(np.linspace(0, 1, nrof_labels))     # create a bunch of colors

for i, r in df.iterrows():
    ax.plot(r['n1'], r['n2'], 'o', markersize=10, color=colors[i], linewidth=0.1, label=r['l'])

ax.set_xlim(0.5, 3.5)
ax.set_ylim(0.5, 3.5)
plt.legend(loc='best')

plt.show()

Answer 4

此外，如果df[l]具有重復的元素，並且必須相應地分配 colors：

import matplotlib.cm as cm
import matplotlib.colors as colors
import numpy as np
import pandas as pd

fig, ax = plt.subplots(figsize=(8,8))

df = pd.DataFrame({'n1':[1,2,1,3], 'n2':[1,3,2,1], 'l':['b','b','c','d']})

l_unq = df['l'].unique()
colormap = cm.viridis
colorlist = [colors.rgb2hex(colormap(i)) for i in np.linspace(0, 0.9, len(l_unq))]

for i,c in enumerate(colorlist):

    x = df[df.l==l_unq[i]].n1
    y = df[df.l==l_unq[i]].n2
    l = l_unq[i]
    ax.scatter(x, y, label=l, s=50, linewidth=0.1, c=c)

ax.set_xlabel('n1')
ax.set_ylabel('n2')
ax.legend()

plt.show()