在MATLAB中，是cellfun总是更换与arrayfun？ [英] In MATLAB, is cellfun always replaceable with arrayfun?

问题描述

我发现在2007年MATLAB的例子，其中 cellfun 和 arrayfun 几乎可以互换使用：

I found an example in MATLAB 2007 in which cellfun and arrayfun can nearly be used interchangeably:

>> cellfun(@(c) c, {'one' 'two' 'three'}, 'uniformoutput', 0)
% ans = 
%    'one'    'two'    'three'
>> arrayfun(@(c) c, {'one' 'two' 'three'})
% ans = 
%    'one'    'two'    'three'

我也能想到，其中 arrayfun 工作，但一个例子 cellfun 并不：

I can also think of an example where arrayfun works but cellfun does not:

>> arrayfun(@(c) c, [1 2 3])
% ans =
%      1     2     3
>> cellfun(@(c) c, [1 2 3])
% ??? Error using ==> cellfun
% Input #2 expected to be a cell array, was double instead.

我的问题是：有没有在 cellfun 的作品，但 arrayfun 没有任何情况呢？如果是，请举例说明。如果没有，为什么 cellfun 甚至有存在的必要？

My question is this: are there any situations in which cellfun works but arrayfun does not? If yes, please give examples. If no, why does cellfun even need to exist?

推荐答案

有可以通过名称在 cellfun 引用，但不能使用一些内置功能在 arrayfun 以同样的方式。从帮助：

There are a few built-in functions that can be referenced by name in cellfun but cannot be used in the same way in arrayfun. From the help:

A = CELLFUN('fun', C), where 'fun' is one of the following strings,
returns a logical or double array A the elements of which are computed
from those of C as follows:

   'isreal'     -- true for cells containing a real array, false
                   otherwise
   'isempty'    -- true for cells containing an empty array, false
                   otherwise
   'islogical'  -- true for cells containing a logical array, false
                   otherwise
   'length'     -- the length of the contents of each cell
   'ndims'      -- the number of dimensions of the contents of each cell
   'prodofsize' -- the number of elements of the contents of each cell

所以 cellfun（'伊斯雷尔'，{一二三化}）是一个有效的前pression，但任何类似的电话 arrayfun 将触发首先输入必须是一个函数句柄错误。

So cellfun('isreal', {'one' 'two' 'three'}) is a valid expression, but any similar call with arrayfun will trigger the First input must be a function handle error.

当然，你可以使用 @isreal 或 @isempty 为 arrayfun

Of course, you can just use @isreal or @isempty for arrayfun

至于为什么 cellfun 仍然存在，我怀疑这是历史上（不打破向后兼容）

As for why cellfun still exists, I suspect it's historical (don't break backward compatibility)

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