Question about finding the number of times an element appears in an array

2 次查看（过去 30 天）
Lewis
Lewis 2021-11-4
评论： Lewis 2021-11-4
Can someone explain why/how this code works in creating an array B which corresponds to the number of each integer from 1-9 in array A?
c=[1:9]
B=sum(A(:)==c, 1)

请先登录，再回答此问题。

采纳的回答

Chris
Chris 2021-11-4
编辑：Chris 2021-11-4
Ran in:
A = randi(9,2)
A = 2×2
8 8 5 9
A(:) formats A in a column vector.
A(:)
ans = 4×1
8 5 8 9
A(:)==c compares the column to each element of c (possible because the dimensions of a and c are orthogonal), returning an nx9 matrix with ones where the comparison is true.
A(:)==1:9
ans = 4×9 logical array
0 0 0 0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 1
Summing across dimension 1 (the default):
B=sum(A(:)==1:9)
B = 1×9
0 0 0 0 1 0 0 2 1

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Matrices and Arrays 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by