rowfun如何知道如何引用表中的变量 [英] How does rowfun know to reference variables inside a table

问题描述

从文档中，我们看到以下示例:

From the documentation, we see the following example:

g = gallery('integerdata',3,[15,1],1);
x = gallery('uniformdata',[15,1],9);
y = gallery('uniformdata',[15,1],2);

A = table(g,x,y)

func = @(x, y) (x - y);

B = rowfun(func,A,...
    'GroupingVariable','g',...
    'OutputVariableName','MeanDiff')

将函数func应用于rowfun中的A时，如何知道A中有名为x和y的变量?

When the function func is applied to A in rowfun how does it know that there are variables in A called x and y?

EDIT :我觉得我的最后一个陈述一定不正确，因为如果您执行A = table(g, y, x)，您将不会获得相同的结果.

EDIT: I feel that my last statement must not be true, as you do not get the same result if you did A = table(g, y, x).

对于rowfun如何使用实际上不使用调用环境中定义的任何变量的函数，我仍然感到困惑.

I am still very confused by how rowfun can use a function that does not actually use any variables defined within the calling environment.

推荐答案

除非您使用Name/Value参数InputVariables指定行(及其顺序)，否则Matlab只会将第1列作为第一个输入，将第2列作为第一个输入第二个输入等，忽略最终的分组列.

Unless you specify the rows (and their order) with the Name/Value argument InputVariables, Matlab will simply take column 1 as first input, column 2 as second input etc, ignoring eventual grouping columns.

因此，为了提高代码的可读性和可维护性，我认为始终显式指定InputVariables是一个好习惯.

Consequently, for better readability and maintainability of your code, I consider it good practice to always specify InputVariables explicitly.

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