How do I find a value in a vector and then create a new vector with those value?

I am having an issue with the following task. How do I create a vector that shows the position of the alphabetic characters as numerical values? Create a vector Alphas that has the numeric positions of all alphabetic characters in TS1. For Example: TS1='%@3Gb6' returns Alphas=[4 5]. I am using the Matlab R2015b software.

Answer 1

[dpb]

>> TS1='%@3Gb6';
>> find(iswithin(TS1,'A','z'))
ans =
   4     5
>> 

>> type iswithin
function flg=iswithin(x,lo,hi)
% returns T for values within range of input
% SYNTAX:
%  [log] = iswithin(x,lo,hi)
%      returns T for x between lo and hi values, inclusive

% Utility routine courtesy dpbozarth (aka dpb)
  flg= (x>=lo) & (x<=hi);

>>

ERRATUM

As noted, forgot there were some characters between the lower- and upper-case ones that will screw up count/position if not accounted for.

find(iswithin(TS1,'A','z') & isletter(TS1))

does work albeit now it may be as simple as to write the regular expression expression.

And, DOH!

find(isletter(TS1))

actually is all that's needed.

[dpb]

Actually, the above isn't exact as there are a few characters between 'z' and 'A'. Just so happens none of them is in the subject string. would have to

Answer 2

[Star Strider]

This is one possibility:

TS1='%@3Gb6';
[AlphaSt,AlphaEnd] = regexp(TS1, '[A-Za-z]+')

AlphaSt =
     4

AlphaEnd =
     5

[Guillaume]

Actually, the simpler regex

pos = regexp(TS1, '[A-Za-z]');

would work better for the OP purpose.

[Star Strider]

Thank you, Guillaume. I’m still learning the best ways to use regexp, and with your demonstrated expertise on this and several other topics, I value your Comments.