从元组生成二维布尔数组 [英] Generate a 2D boolean array from tuples

问题描述

如何使用显示True值索引的元组列表生成2D布尔数组?

How can I generate a 2D boolean array using a list of tuples that shows the indices of the True values?

例如，我具有以下元组列表:

For example I have the following list of tuples:

lst = [(0,1), (0, 2), (1, 0), (1, 3), (2,1)]

我要做的是，我首先生成一个False数组:

What I do is, I first generate an array of False's:

arr = np.repeat(False, 12).reshape(3, 4)

然后，遍历列表以分配True值:

Then, iterate over the list to assign True values:

for tup in lst:
    arr[tup] = True
print(arr)
array([[False,  True,  True, False],
       [ True, False, False,  True],
       [False,  True, False, False]], dtype=bool)

在我看来，这是一个常见的用例，所以我想知道是否有一个内置方法，没有循环.

It seems like a common use case to me so I was wondering if there is a built-in method for this, without the loops.

推荐答案

zip(*...)是转置"列表列表(或元组)的便捷方法.并且A[x,y]与A[(x,y)]相同.

zip(*...) is a handy way of 'transposing' a list of lists (or tuples). And A[x,y] is the same as A[(x,y)].

In [397]: lst = [(0,1), (0, 2), (1, 0), (1, 3), (2,1)]

In [398]: tuple(zip(*lst))    # make a tuple of tuples (or lists)
Out[398]: ((0, 0, 1, 1, 2), (1, 2, 0, 3, 1))

In [399]: A=np.zeros((3,4),dtype=bool)  # make an array of False

In [400]: A[tuple(zip(*lst))] = True  # assign True to the 5 values

In [401]: A
Out[401]: 
array([[False,  True,  True, False],
       [ True, False, False,  True],
       [False,  True, False, False]], dtype=bool)

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