Matlab中cellfun函数的使用

hxsyl 2021-12-22 原文

Compute the mean of each vector in cell array C.

C = {1:10, [2; 4; 6], []};

averages = cellfun(@mean, C)
This code returns

averages =
    5.5000    4.0000       NaN

…………………………………………………….

　　该函数就是专门对cell数组进行操作的，个人认为是代替了传统的for循环，和C语言不一个思想，主要是行列化矩阵，一次处理。

　　比如a = {[1 2 3] [4 5 6]},那么cellfun(@length,a)得到6。线cell2mat也可以吧，然后分别计算，在累加。

Compute the size of each array in C, created in the previous example.

[nrows, ncols] = cellfun(@size, C)
This code returns

nrows =
     1     3     0
ncols =
    10     1     0

　　………………………………………………….

　　cellfun中使用自定义函数对cell数组进行处理；既然可以自定义函数，那么cellfun中的的中间部分的参数个数和自定义函数需要的参数数目相同。

　　还能这么用。

queryNearestNeighborIds = cellfun( @(vector, index) vector(index), queryCandidateIds, queryNearestNeighborIds, \'UniformOutput\', false );

　　…………………………………………

Create a cell array that contains strings, and abbreviate those strings to the first three characters. Because the output strings are nonscalar, set UniformOutput to false.

days = {\'Monday\', \'Tuesday\', \'Wednesday\', \'Thursday\', \'Friday\'};

abbrev = cellfun(@(x) x(1:3), days, \'UniformOutput\', false)
The syntax @(x) creates an anonymous function. This code returns

abbrev = 
    \'Mon\'    \'Tue\'    \'Wed\'    \'Thu\'    \'Fri\'