How to find the position of a specific characters containing in a string in a cell array

hello. i have a 136x39 cell array like this one

'Data Name' 'Timestamp' 360 370

'001-Day 1-RE-1' '24/07/2014 10:17:10' -738.803345332164 -734.184486898226

'001-Day 1-RW-1' '24/07/2014 10:17:37' -707.272295650121 -703.634423319119

'001-Day 1-LE-1' '24/07/2014 10:19:20' -744.635983922777 -740.346463517543

'001-Day 1-LW-1' '24/07/2014 10:19:39' -751.552763303339 -747.041101104821

and I want to find the positions of 'RE','RW','LE','LW'. I tried with the function [RW1, RW2]=find(strcmp('RW', array)); but got no results. I also tried [RW1, RW2]=find(strcmp('*RW*', Acdelta)); or strfind..

Any ideas?

Many thanks

Answer 1

[Guillaume]

Use either strfind four times, once for each pattern (RE, RW, LE, LW). Note that strfind (and strcmp) does not accept wildcards, or regexp

pos = regexp(array(:, 1), 'RE|RW|LE|LW', 'once');

Note that you can't pass the full cell array to strfind or regexp, since it contains elements that are not strings. Here, I just pass the first column.

Also, in your example, the position is always the same, so why do you want to find it?

[Jo]

Many thanks for your answer. Very helpful. The position is not always the same, there is a row of data like '001-day1-RE-1' , '001-day1-RE-2', '001-day1-RW-1' ,'001-day1-RW-2' ,'001-day2-RE-1' etc.. and in each one correspond a different value. I want to find these positions along with the values in order to calculate the mean.

[Guillaume]

It may be an issue of language, but in any of your example the position of 'RE' or 'RW' is always at the 10th character.

Is what you're looking for actually the value following 'RE' or 'RW', i.e. either the 2 or the 1?

[Jo]

yes you are right. 'RE', 'RW' is the 10th character in this array but it may change in a different one, that's why I am looking for 'RE', 'RW' only. Each of 'RE', 'RW', appears to have 4 different values for each day (day1, day2,..). So I want to find the positions (values) and calculate the mean for each day. In a different array, where 'LW' wasn't part of a string, I used the function [LW1, LW2]=find(strcmp('LW', array)), found the positions of LW and calculated the mean as I described above.

[Guillaume]

Ok, I'm still not very clear on what you're trying to do and whether or not your question is actually answered.

If you want the position and the value that follows the 'RE/RW/LE/LW', you can use a different regular expression:

[pos, valuestr] = regexp(array(:, 1), '(?:RE|RW|LE|LW)-(\d+)', 'start', 'tokens', 'once');
values = cellfun(@(v) str2double(v), valuestr, 'UniformOutput', false);