How can I use the content of a variable to call another variable?

Question

David 2014-8-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/151341-how-can-i-use-the-content-of-a-variable-to-call-another-variable

编辑： Stephen23 2023-9-12

I'm confronted with the following problem:

eur2usd =[ 1.3 1.2 1.1];
eur2cad =[0.8 0.9 0.7];
currency = 'eur2usd'

I would like to use the variable currency to call the content of eur2usd ([ 1.3 1.2 1.1]). So that if currency = 'eur2cad', I can call the content of eur2cad by using the variable currency.

2 个评论
显示无隐藏无

Adam 2014-8-18

I would favour coming up with a solution which didn't require you to do that. e.g. having currency be a function handle rather than a raw variable-name string, or using containers.Map or some kind of array to index into.

But if you are set on having a variable name in a string I'm sure someone can soon furnish you with the appropriate eval-based syntax.

Stephen23 2015-1-4

编辑：Stephen23 2023-9-12

在 MATLAB Online 中打开

Basically you should not do this.

Using dynamically defined variable names or encoding data within the variable name is a pretty bad approach:

https://www.mathworks.com/matlabcentral/answers/304528-tutorial-why-variables-should-not-be-named-dynamically-eval

You should probably be using for your data: structures. This shows how it could work:

>> A = struct('eur2usd',[ 1.3 1.2 1.1],'eur2cad',[0.8 0.9 0.7]);
>> A.('eur2cad')
ans = [0.8,0.9,0.7]

Note that using a structure is extendable to any number of currencies without cluttering-up your workspace with a thousand variables. There is also a large selection of tools that you can use to manipulate structures, their fields and contents:

http://www.mathworks.com/help/matlab/structures.html

Summary: do not use eval to encode (meta-)data into the variable names!

请先登录，再进行评论。

请先登录，再回答此问题。