Python：连接（或克隆）一个 numpy 数组 N 次

Python: Concatenate (or clone) a numpy array N times

提问by stelios

I want to create an MxN numpy array by cloning a Mx1 ndarray N times. Is there an efficient pythonic way to do that instead of looping?

我想通过克隆 Mx1 ndarray N 次来创建一个 MxN numpy 数组。有没有一种有效的pythonic方法来做到这一点而不是循环？

Btw the following way doesn't work for me (X is my Mx1 array) :

顺便说一句，以下方式对我不起作用（X 是我的 Mx1 数组）：

   numpy.concatenate((X, numpy.tile(X,N)))

since it created a [M*N,1] array instead of [M,N]

因为它创建了一个 [M*N,1] 数组而不是 [M,N]

采纳答案by Cory Kramer

You are close, you want to use np.tile, but like this:

你很接近，你想使用np.tile，但像这样：

a = np.array([0,1,2])
np.tile(a,(3,1))

Result:

结果：

array([[0, 1, 2],
   [0, 1, 2],
   [0, 1, 2]])

If you call np.tile(a,3)you will get concatenatebehavior like you were seeing

如果你打电话，np.tile(a,3)你会得到concatenate像你看到的那样的行为

array([0, 1, 2, 0, 1, 2, 0, 1, 2])

http://docs.scipy.org/doc/numpy/reference/generated/numpy.tile.html

http://docs.scipy.org/doc/numpy/reference/generated/numpy.tile.html

回答by Samy Arous

Have you tried this:

你有没有试过这个：

n = 5
X = numpy.array([1,2,3,4])
Y = numpy.array([X for _ in xrange(n)])
print Y
Y[0][1] = 10
print Y

prints:

印刷：

[[1 2 3 4]
 [1 2 3 4]
 [1 2 3 4]
 [1 2 3 4]
 [1 2 3 4]]

[[ 1 10  3  4]
 [ 1  2  3  4]
 [ 1  2  3  4]
 [ 1  2  3  4]
 [ 1  2  3  4]]

回答by atomh33ls

You could use vstack:

你可以使用vstack：

numpy.vstack([X]*N)

e.g.

例如

    >>> import numpy as np
    >>> X = np.array([1,2,3,4])
    >>> N = 7
    >>> np.vstack([X]*N)
    array([[1, 2, 3, 4],
           [1, 2, 3, 4],
           [1, 2, 3, 4],
           [1, 2, 3, 4],
           [1, 2, 3, 4],
           [1, 2, 3, 4],
           [1, 2, 3, 4],
           [1, 2, 3, 4],
           [1, 2, 3, 4]])