如何将一个函数的多个输出直接传递给另一个? [英] How to directly pass multiple outputs of a function to another?
问题描述
<$ c $ c> a = sin(sqrt(8));
现在考虑包含两个步骤来计算 R
,其中 X
和 Y
作为中间输出。
[X,Y] = meshgrid(-2:2,-2:2);
[〜,R] = cart2pol(X,Y);
通常有两种方法可以将两个函数结合起来的中间产出?例如,我怎样才能写出类似于 [〜,R] = cart2pol(meshgrid(-2:2,-2)2)
的东西,它和前面的代码一样注意:是什么让我的问题与是在我的情况下,外部函数接受多个输入。因此,我不能也不想将第一个函数的输出组合到一个单元阵列中。我想让它们分别传递给第二个函数。
要回答标题中的问题:使用以下函数,可以将函数的多个输出重定向到另一个函数:
函数varargout = redirect(source (源,目标,n_output_source,which_redirect_from_source,varargin)
%(重定向(源,目标,n_output_source,which_redirect_from_source,...)
%重定向函数(源)的输出到另一个函数)
%source:函数指针
%destination:函数指针
%n_output_source:源函数的输出数(选择最佳过载函数)
%which_redirect_from_source:被重定向
%varargin参数到源函数
output = cell(1,n_output_source);
[output {:}] = source(varargin {:});
varargout = cell(1,max(nargout,1));
[va rargout {:}] =目标(输出{which_redirect_from_source});
end
现在我们可以将它应用到示例中:
[〜,R] =重定向(@ meshgrid,@ cart2pol,2,[1,2],-2:2,-2:2)
这里,源函数有2个输出,我们希望将输出1和2从源重定向到目标。 -2:2是源函数的输入参数。
处理上述示例的其他方法:如果您可以使用GNU Octave,并且 bsxfun
和 nthargout
,这是您的解决方案:
R = bsxfun(@(a,b)nthargout(2,@ cart2pol,a,b),( - 2:2)' ,( - 2:2))
在Matlab中一个可能的解决方案是:
[〜,R] = cart2pol(meshgrid(-2:2),transpose(meshgrid(-2:2)))
或
函数R = cart2pol2(m)
[〜,R] = cart2pol(m,m')
结束
$ b cart2pol2(meshgrid(-2:2,-2:2) )
Let me elaborate with examples: We know how to easily combine functions with a single output:
a = sin(sqrt(8));
Now consider this example code containing two steps to calculate R
, with X
and Y
as intermediate outputs.
[X, Y] = meshgrid(-2:2, -2:2);
[~, R] = cart2pol(X, Y);
In general is there a way to combine the two functions and get rid of intermediate outputs? For instance how can I write something similar to [~, R] = cart2pol(meshgrid(-2:2, -2:2))
that works same as the previous code?
Note: What makes my question different from this question is that in my case the outer function accepts multiple inputs. Therefore I cannot and do not want to combine the outputs of the first function into one cell array. I want them to be passed to the second function separately.
To answer the question in the title: Using the following function, it is possible to redirect multiple outputs of a function to another:
function varargout = redirect(source, destination, n_output_source, which_redirect_from_source, varargin)
%(redirect(source, destination, n_output_source, which_redirect_from_source,....)
%redirect output of a function (source) to input of another function(destination)
% source: function pointer
% destination: function pointer
% n_output_source: number of outputs of source function (to select best overload function)
% which_redirect_from_source: indices of outputs to be redirected
% varargin arguments to source function
output = cell(1, n_output_source);
[output{:}] = source(varargin{:});
varargout = cell(1, max(nargout,1));
[varargout{:}] = destination(output{which_redirect_from_source});
end
And now we can apply it to the example:
[~,R] = redirect(@meshgrid,@cart2pol, 2, [1, 2], -2:2, -2:2)
Here, source function has 2 outputs and we want to redirect outputs 1 and 2 from source to destination. -2:2 is the input argument of the source function.
Other way to deal with the mentioned example: If you can use GNU Octave, with bsxfun
and nthargout
this is your solution:
R = bsxfun(@(a,b) nthargout(2, @cart2pol,a,b),(-2:2)',(-2:2))
in Matlab a possible solution is:
[~, R] = cart2pol(meshgrid(-2:2), transpose(meshgrid(-2:2)))
or
function R = cart2pol2(m)
[~,R] = cart2pol(m,m')
end
cart2pol2(meshgrid(-2:2, -2:2))
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