如何在numpy.fromfunction内使用范围? [英] How can I use a range inside numpy.fromfunction?

问题描述

我正在尝试创建一个矩阵，该矩阵的索引(i，j)值对于我正在定义的函数为f(i,j),.我正在尝试使用numpy.fromfunction来执行此操作，但无法使其正常工作.这是代码

I'm trying to create a matrix whose value at index (i,j) will be f(i,j), for a function that I'm defining. I'm trying to do this with numpy.fromfunction and I haven't been able to get it to work. Here's the code

import numpy as np

def f(i,j):
    return sum((i+1)//k for k in np.arange(1,j+2))

def M(N):
    shape = np.array([N,N])
    np.fromfunction(f, shape,dtype = np.int)

A= M(5)   

我收到错误

builtins.TypeError:只能将长度为1的数组转换为Python标量

builtins.TypeError: only length-1 arrays can be converted to Python scalars

在fromfunction的调用中，

我想它必须与np.arange有关.

in the call to fromfunction and I suppose it must have to do with np.arange.

最初，我有range(1,j+2)，但是随后出现错误

Originally, I had range(1,j+2) but then I got the error

TypeError:仅整数标量数组可以转换为标量索引

TypeError: only integer scalar arrays can be converted to a scalar index

能告诉我我需要做什么吗?

Can you tell me what I need to do, please?

推荐答案

我认为您必须先vectorize f:

>>> np.fromfunction(np.vectorize(f), (5, 5), dtype=int)
array([[ 1,  1,  1,  1,  1],
       [ 2,  3,  3,  3,  3],
       [ 3,  4,  5,  5,  5],
       [ 4,  6,  7,  8,  8],
       [ 5,  7,  8,  9, 10]])

实际上，fromfunction并非一次就传递坐标，而是一次传递:

Indeed, fromfunction passes the coordinates not one-by-one but in one go:

>>> def f(i, j):
...     print(i, j)
...     return sum((i+1)//k for k in range(1, j+2))
... 
>>> np.fromfunction(f, (5, 5), dtype=int)
[[0 0 0 0 0]
 [1 1 1 1 1]
 [2 2 2 2 2]
 [3 3 3 3 3]
 [4 4 4 4 4]] [[0 1 2 3 4]
 [0 1 2 3 4]
 [0 1 2 3 4]
 [0 1 2 3 4]
 [0 1 2 3 4]]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/paul/local/lib/python3.6/site-packages/numpy/core/numeric.py", line 1914, in fromfunction
    return function(*args, **kwargs)
  File "<stdin>", line 3, in f
TypeError: only integer scalar arrays can be converted to a scalar index

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