关于如何使用matplotlib.colorbar的细节

Question

问题：

我有两列数据（public static long getThreadId(Context context, String phoneNumber) { Uri threadIdUri = Uri.parse("content://mms-sms/threadID"); Uri.Builder uriBuilder = threadIdUri.buildUpon(); uriBuilder.appendQueryParameter("recipient", phoneNumber); Uri uri = uriBuilder.build(); Cursor cursor = context.getContentResolver().query(uri, new String[]{"_id"} /* projection */, null /* selection */, null /* selectionArgs */, null /* order */); if (cursor != null) { try { if (cursor.moveToFirst()) { return cursor.getLong(0); } } finally { cursor.close(); } } return 0; } 和x点），第三列有标签（值y或0）。我想在散点图上绘制1和x，并根据标签是y还是0对其进行着色，我想要一个右边的颜色条剧情。

以下是我的数据：https://www.dropbox.com/s/ffta3wgrl2vvcpw/data.csv?dl=0

注意：我知道因为只有两个标签，所以尽管使用了颜色条，我只会得到两种颜色;但这个数据集仅用作示例。

到目前为止我做了什么

1

由于对import matplotlib.pyplot as plt import csv import matplotlib as m #read in the data with open('data.csv', 'rb') as infile: data=[] r = csv.reader(infile) for row in r: data.append(row) col1, col2, col3 = [el for el in zip(*data)] #I'd like to have a colormap going from red to green: cdict = { 'red' : ( (0.0, 0.25, 0), (0.5, 1, 1), (1., 0.0, 1.)), 'green': ( (0.0, 0.0, 0.0), (0.5, 0.0, 0.0), (1., 1.0, 1.0)), 'blue' : ( (0.0, 0.0, 0.0), (1, 0.0, 0.0), (1., 0.0, 0.0))} cm = m.colors.LinearSegmentedColormap('my_colormap', cdict) # I got the following line from an example I saw; it works for me, # but I don't really know how it works as an input to colorbar, # and would like to know. formatter = plt.FuncFormatter(lambda i, *args: ['0', '1'][int(i)]) plt.figure() plt.scatter(col1, col2, c=col3) plt.colorbar(ticks=[0, 1], format=formatter, cmap=cm) 的调用，上述代码无效。

1. 如何让它发挥作用（缺少什么），这是最好的方法吗？

2. 关于plt.colorbar参数的文档对我来说是不可理解的。究竟是什么？

   文档：http://matplotlib.org/api/figure_api.html#matplotlib.figure.Figure.colorbar

Answer 1

你需要传递col3作为浮点数组散布，而不是元组，而不是整数

所以，这应该有效：

import matplotlib.pyplot as plt
import csv
import matplotlib as m
import numpy as np

#read in the data
with open('data.csv', 'rb') as infile:
    data=[]
    r = csv.reader(infile)
    for row in r:
    data.append(row)

col1, col2, col3 = [el for el in zip(*data)]

#I'd like to have a colormap going from red to green:
cdict = {
    'red'  :  ( (0.0, 1.0, 1.0), (0.5, 0.0, 0.0), (1.0, 0.0, 0.0)),
    'green':  ( (0.0, 0.0, 0.0), (0.5, 0.0, 0.0), (1.0, 1.0, 1.0)),
    'blue' :  ( (0.0, 0.0, 0.0), (1.0, 0.0, 0.0), (1.0, 0.0, 0.0))}  

cm = m.colors.LinearSegmentedColormap('my_colormap', cdict)

#I got the following line from an example I saw; it works for me, but I don't really know how it works as an input to colorbar, and would like to know.
formatter = plt.FuncFormatter(lambda i, *args: ['0', '1'][int(i)])

plt.figure()
plt.scatter(col1, col2, c=np.asarray(col3,dtype=np.float32),lw=0,cmap=cm)
plt.colorbar(ticks=[0, 1], format=formatter, cmap=cm)

对于ticks，您要在颜色栏上传递一个列表。因此，在您的示例中，您的刻度为0，刻度为1。

我还修复了你的cmap，从红色变为绿色。你需要告诉散点图也使用cmap。