散点图颜色栏-Matplotlib [英] Scatter plot colorbar - Matplotlib

问题描述

我正在尝试显示散点图的颜色条，但我一直在收到错误消息:

TypeError:您必须首先为可映射设置set_array

这就是我要绘制的内容:

# Just plotting the values of data that are nonzero 
x_data = numpy.nonzero(data)[0] # x coordinates
y_data = numpy.nonzero(data)[1] # y coordinates

# Mapping the values to RGBA colors
data = plt.cm.jet(data[x_data, y_data])

pts = plt.scatter(x_data, y_data, marker='s', color=data)

plt.colorbar(pts)

如果我在行plt.colorbar(pts)上添加注释，则可以正确绘制图形，但是我也想绘制颜色条.

谢谢.

解决方案

您要传递特定的rgb值，因此matplotlib无法构造颜色图，因为它不知道其与原始数据的关系. /p>

让scatter代替您将值映射为RGB颜色.

代替:

# Mapping the values to RGBA colors
data = plt.cm.jet(data[x_data, y_data])

pts = plt.scatter(x_data, y_data, marker='s', color=data)

做:

pts = plt.scatter(x_data, y_data, marker='s', c=data[x_data, y_data])

(只需将您最初传递给plt.cm.jet的内容传递到c.)

然后，您将能够正常构建颜色图.特定的错误是告诉您颜色是手动设置的，而不是通过set_array(用于处理将数据值数组映射到RGB)设置的.

I'm trying to show a color bar of my scatter plot but I'm keep getting the error:

TypeError: You must first set_array for mappable

This is what I'm doing to plot:

# Just plotting the values of data that are nonzero 
x_data = numpy.nonzero(data)[0] # x coordinates
y_data = numpy.nonzero(data)[1] # y coordinates

# Mapping the values to RGBA colors
data = plt.cm.jet(data[x_data, y_data])

pts = plt.scatter(x_data, y_data, marker='s', color=data)

plt.colorbar(pts)

If I comment the line plt.colorbar(pts) I got the plot correctly, but I would like to plot the color bar too.

Thank you in advance.

解决方案

You're passing in specific rgb values, so matplotlib can't construct a colormap, because it doesn't know how it relates to your original data.

Instead of mapping the values to RGB colors, let scatter handle that for you.

Instead of:

# Mapping the values to RGBA colors
data = plt.cm.jet(data[x_data, y_data])

pts = plt.scatter(x_data, y_data, marker='s', color=data)

Do:

pts = plt.scatter(x_data, y_data, marker='s', c=data[x_data, y_data])

(Just pass in to c what you were originally passing into plt.cm.jet.)

Then you'll be able to construct a colormap normally. The specific error is telling you that the colors have been manually set, rather than set through set_array (which handles mapping an array of data values to RGB).

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