Scatter()至少接受2个参数(给定1个)

I'm new to this and I'm trying to represent a structured array, npy file as a scatter plot. I'm not entirely sure what my other argument should be. I was thinking that I should span out my values for x and y, but I am not sure.

我是新的，我试着表示一个结构化的数组，npy文件作为散点图。我不完全确定我的另一个论点应该是什么。我想我应该把x和y的值展开，但我不确定。

import matplotlib.pyplot as plt
import numpy as np
import os

path = '/users/username/Desktop/untitled folder/python     files/MSII_phasespace/'

os.chdir( path )

data = np.load('msii_phasespace.npy',mmap_mode='r')

# data.size: 167197
# data.shape: (167197,)
# data.dtype: dtype([('x', '<f4'), ('y', '<f4'), ('z', '<f4'),
  # ('velx', '<f4'), ('vely', '<f4'), ('velz', '<f4'), ('m200', '<f4')])

plt.title ("MS II data structure")
plt.xlabel(r'$\Omega_{\mu \nu}$')
plt.ylabel(r'$\Omega^{\mu \nu}$')

plt.scatter(data)
plt.show()

Inputting this outputs the error:

输入输出错误:

TypeError: scatter() takes at least 2 arguments (1 given)

TypeError: scatter()至少接受2个参数(给定1个)

2 个解决方案

#1

You have a structured array there. Matplotlib does not know what to do with it. As given in the documentation for matplotlib.pyplot.scatter() you need to specify two input arrays x, and y.

这里有一个结构化数组。Matplotlib不知道怎么处理它。如matplotlib.pyplot.scatter()文档中所示，您需要指定两个输入数组x和y。

From the dtype output, I gather that your structured array has values for 'x', 'y', 'z', 'velx', 'vely', 'velz', and 'm200'. I have no clue what they are, but in order to create a scatter plot, you need to specify two components, e.g.:

从dtype输出中，我估计您的结构化数组具有'x'、'y'、'z'、'velx'、'vely'、'velz'和'm200'的值。我不知道它们是什么，但是为了创建散点图，您需要指定两个组件，例如:

plt.scatter(data['x'], data['y'])

Assuming that 'm200' should be mapped to the width of the scatter points, you could use:

假设“m200”应该映射到散点的宽度，您可以使用:

plt.scatter(data['x'], data['y'], s=data['m200'])

#2

plt.scatter needs at least two arguments (which the error states quite clearly).

plt。散点至少需要两个参数(错误描述得很清楚)。

If you look into the docs (http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.scatter), you will see this signature:

如果您查看文档(http://matplotlib.org/api/pyplot_api.html#matplotlib.pyplot.scatter)，您将看到以下签名:

scatter(x, y, s=20, c=None, marker='o', cmap=None, norm=None, vmin=None, vmax=None, alpha=None, linewidths=None, verts=None, edgecolors=None, hold=None, data=None, **kwargs)

So you need to provide at least an array for each x and y values:

因此，你需要为每个x和y值提供至少一个数组:

plt.scatter(data['x'], data['y'])

Starting from matplotlib 1.5, you could also use this syntax to access data from a structured array:

从matplotlib 1.5开始，您还可以使用此语法从结构化数组访问数据:

plt.scatter('x', 'y', data=data)

#1