how to make a variable name from a string

2013a version

>> test='eye'
>> value = [5,5,3]

value =

       5     5     3

>> eval([sprintf(test) '= data+1']);
Index exceeds matrix dimensions.

How to fix this error? Thank you for helping!

Answer 1

[kjetil87]

The error should not appear, your code looks to work exept for the part of 'data' , should this instead be value?

test='eye';
value=[1,2,3];
eval([sprintf(test) '=value+1'])

eye =

       2     3     4

The index exceeds matrix dimension could be related to that you have at some point declared a variable in your workspace ( or funciton or whatever ) with the name of eval.

try typing

which eval

it should return that eval is a built-in function, if it returns eval is a variable there is the reason for your error. If so just use

clear eval

[kjetil87]

also the sprintf is not really needed. + also check out

http://www.mathworks.se/help/matlab/ref/assignin.html

[xianghong]

when I tried this morning, it worked! Thank you so much! Have a great week!

Xianghong

Answer 2

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

Answer 3

[xianghong]

This seems like to name the fields within a variable. If I just want to make a variable name from a string, how to do it? Thanks!

[Walter Roberson]

No, it is not just for creating field names within a variable. It shows a number of different alternatives to creating a variable from a string, recommending strongly that you use one of the alternatives instead of creating a variable dynamically. At the end of the FAQ it shows how to create a variable dynamically, for the rare case when you really need to do that. If you are not engaged in creating extensions to MATLAB itself, chances are that there is a better route than creating a variable dynamically.

Answer 4

[xianghong]

EDU>> test='eye';

EDU>> value=[1,2,3];

EDU>> eval([sprintf(test) '=value+1'])

Index exceeds matrix dimensions.

Looks like it still gave the error. What shall I do?

Thanks,

[Walter Roberson]

Please use the command

clear eval

and then try again

[xianghong]

thank you so much! It worked this monday morning!

Have a nice day!

Xianghong