问题描述
这是一个有点愚蠢的问题,但我似乎无法弄清楚如何在matlab中进行置换.以文档示例为例:
This is a somewhat silly question but I can't seem to figure out how permute works in matlab. Take the documentation example:
A = [1 2; 3 4]; permute(A,[2 1])
ans =
1 3
2 4
这是怎么回事?这如何告诉Matlab 3和2需要交换?
What is going on? How does this tell matlab that the 3 and 2 need to be swapped?
推荐答案
permute
对数组的尺寸进行排列,而不是对数组元素的排列,正如人们可能希望从其名称中得出的那样.
permute
does a permutation of the dimensions of an array, not of its elements, as one may expect from its name.
因此,permute(A,[2,1])
将数组A
的维度2(列)与数组A
的维度1(行)翻转,这等效于转置(A'
).
Thus, permute(A,[2,1])
flips dimension 2 (the columns) of array A
with dimension 1 (the rows) of array A
, which is equivalent to a transpose (A'
).
permute(A,[3,2,1])
将产生一个1×2×2数组(因为size(A,3)==1
),其中该数组水平翻转".
permute(A,[3,2,1])
would produce a 1-by-2-by-2 array (because size(A,3)==1
), where the array is "flipped up horizontally".
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