Python 向散点图添加图例

这个问题已经被问到了，但我想找到一个更清楚的解决办法

给定X是100x2数据，标签是标签向量（从1到9），我绘制散点图如下：

pl.scatter(X[:,0], X[:,1], c = labels)
pl.show()

如何添加图例来解释一行代码中的颜色？其他解决方案分别绘制每个标签：

a = pl.scatter(X1[:,0], X1[:,1], color = "red")
b = pl.scatter(X2[:,0], X2[:,1], color = "green")
c = pl.scatter(X3[:,0], X3[:,1], color = "blue")
pl.legend((a,b,c), ("line 1", "line 2", "line 3")
pl.show()

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只需标记每个绘图并调用图例（），就像您所做的那样：）

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可以使用所需图例创建虚拟散点图，如下所示：

pl.scatter(X[:,0], X[:,1], c = labels)

for item in labels:
    #dummy plot just to create the legend
    pl.scatter([], [], c = item, label = item)
#loc = 0 is for the best position of the legend
#scatterpoints = 1 will only show one point in the legend instead of multiple points
plt.legend(loc = 0, scatterpoints = 1)
pl.show()

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我知道您可能已经看到了这一点，但如果您没有看到：只需标记每个绘图并调用图例（）：plt.scatter（x1，y1，label=str（pointset1））。。。；plt.图例（loc='右上角'，numpoints=1，ncol=3，fontsize=8，bbox_to_anchor=（1,1））；plt.show（）

pl.scatter(X[:,0], X[:,1], c = labels)

for item in labels:
    #dummy plot just to create the legend
    pl.scatter([], [], c = item, label = item)
#loc = 0 is for the best position of the legend
#scatterpoints = 1 will only show one point in the legend instead of multiple points
plt.legend(loc = 0, scatterpoints = 1)
pl.show()