Convert a string into a function of x

2018 11 21
2 个回答
回答已采纳
更新时间：2023 1 12
9 次查看（30 天）

0 个投票

Hi all,
I have created a string like this:
Sstr = join(compose('(x(%d:%d)-x(%d:%d))))', A), ' + ')
so I get a result:
Sstr='(x(2:180)-x(1:179)+(x(182:360)-x(181:359))'
Is it possible to convert the string into a function of x like this??:
f=@(x) (x(2:180)-x(1:179)+(x(182:360)-x(181:359))
thanks
Nikolas

1 个评论
显示 -1更早的评论 隐藏 -1更早的评论

Here is the code
A=[2 180 1 179 182 360 181 359];
str = join(compose('(x(%d:%d)-x(%d:%d))', A), ' + ')

请先登录，再进行评论。

请先登录，再回答此问题。

 采纳的回答

Stephen23
Stephen23 2018-11-21
编辑：Stephen23 2018-11-21

2 个投票

You can use str2func:
fun = str2func(['@(x)',Sstr]);
and then call it just like any other function.

4 个评论
显示 2更早的评论 隐藏 2更早的评论

well I get an error like this
Undefined function 'str2func' for input arguments of type 'cell'.
Maybe it's my matlab version it's 2017a.
is there any other option?
thanks
Stephen23
Stephen23 2018-11-21
编辑：Stephen23 2018-11-21
"Maybe it's my matlab version it's 2017a."
You wrote in your question "so I get a result:"
Sstr='(x(2:180)-x(1:179)+(x(182:360)-x(181:359))'
But it turns out that you actually have a cell array of character vectors, not a single character vector like you showed us. How do you expect to convert a cell array of character vectors to one function? Answer: you need to actually convert that cell array of character vectors into one character vector, just like you showed in your question.
"is there any other option?"
To do what? Convert a string to a function? No, not really. To convert your array A to a function? Quite possibly.
Well I solved my problem by converting the cell to a character like this:
g = cell2mat(Sstr)
f = str2func(['@(x)' g])
thanks for the comments !
Stephen23
Stephen23 2018-11-21
@Nikolas Spiliopoulos: you should check the contents of g to make sure that they make sense.
Don't forget to accept my answer if it helped you!

请先登录，再进行评论。

更多回答（1 个）

KRISHNA MAHTO
KRISHNA MAHTO 2023-1-12
编辑：KRISHNA MAHTO 2023-1-12
Ran in:

0 个投票

Ran in:
i have taken string as an input form the user ,, and want data to be converted into funtion of x and y , by the program itself ,,,for easy usage ,
%code to take input form the user -
prompt = "input U:-"
prompt = "input U:-"
u = input(prompt,"s")
Unable to run the 'fevalJSON' function because it calls the 'input' function, which is not supported for this product offering.
prompt = "input V:-"
v = input(prompt ,"s")

类别

在 帮助中心 和 File Exchange 中查找有关 Characters and Strings 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by