Working string in MATLAB

Question

I have the following string in MATLAB, for example

@#%%F1_USA(40)_u

and I want

F1_USA_40__u

Does it has any function for this?

What exactly do you want? Strip all the non-alphanumeric characters, except the parentheses which should be replaced by underscores instead? — Tamás
– Tamás, Commented Apr 28, 2011 at 9:48
From the beginning of the word I want to remove the non-alphanumeric characters and in the words I want to replace with '_' — Mokus
– Mokus, Commented Apr 28, 2011 at 9:50

Tamás · Accepted Answer · 2011-04-28 10:00:50Z

2

Your best bet is probably regexprep which allows you to replace parts of a string using regular expressions:

s_new = regexprep(regexprep(s, '[()]', '_'), '[^A-Za-z0-9_]', '')

Update: based on your updated comment, this is probably what you want:

s_new = regexprep(regexprep(s, '^[^A-Za-z0-9_]*', ''), '[^A-Za-z0-9_]', '')

or:

s_new = regexprep(regexprep(s, '[^A-Za-z0-9_]', '_'), '^_*', '')

edited Apr 28, 2011 at 10:00

answered Apr 28, 2011 at 9:54

Tamás

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2 Comments

gnovice Over a year ago

There is a typo in the first solution of your update. You should have a '_' instead of a '' at the end. Also, using cell array inputs for the expressions and replacement strings will allow you to make just one call to REGEXPREP.

Tamás Over a year ago

The first solution refers to the stage when it was unclear what the OP wanted - I have assumed that he wants to replace parentheses with underscores and then strip everything that is not alphanumeric or an underscore. Also, thanks for the link, I didn't know about that. Very useful!

Community · Accepted Answer · 2017-05-23 11:43:40Z

1

One way to do this is to use the function ISSTRPROP to find the indices of alphanumeric characters and replace or remove the others accordingly:

>> str = '@#%%F1_USA(40)_u';           %# Sample string
>> index = isstrprop(str,'alphanum');  %# Find indices of alphanumeric characters
>> str(~index) = '_';                  %# Set non-alphanumeric characters to '_'
>> str = str(find(index,1):end)        %# Remove any leading '_'

str =

F1_USA_40__u                           %# Result

If you want to use regular expressions (which can get a little more complicated) then the last suggestion from Tamas will work. However, it can be greatly simplified to the following:

str = regexprep(str,{'\W','^_*'},{'_',''});

edited May 23, 2017 at 11:43

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answered Apr 28, 2011 at 16:18

gnovice

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