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Converting rough strings to exact strings

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I have a string array of filenames which are names in an semi-consistent manner, e.g.:
AllFiles
AllFiles =
4x1 string array
"textIdontCareAbout_Phenolic32_Group5_textIdontCareAbout"
"textIdontCareAbout_P1_textIdontCareAbout"
"textIdontCareAbout_Epx2_G3_textIdontCareAbout"
"textIdontCareAbout_Epoxy_105_textIdontCareAbout"
Im trying to figure out how to extract & convert the inconsistent substrings of interest (the stuff between "textIdontCareAbout") into a consistent format, e.g.:
AllFiles
AllFiles =
4x1 string array
"P32G5"
"P1"
"E2G3"
"E105"
I had been avoiding using regexp, but having caved and decided to work with that, I'm trying to figure out an elegant way to do this conversion. At present the only thing I can see working is manually checking for each possible phrasing style I see when manualy searching through the data I have at present.
Is there a better way to go about this, or even just some suggestions to how to define the regexp in a way to have as few searches as possible?
  4 Comments
Paul
Paul on 8 Sep 2022
There may be a way to do this with string operations. Hard to tell w/o knowing the rule(s) to apply for what to keep and what to discard from a single string. For example, supposing that @the cyclist has the correct rules, one could do
AllFiles = [
"textIdontCareAbout_Phenolic32_Group5_textIdontCareAbout"
"textIdontCareAbout_P1_textIdontCareAbout"
"textIdontCareAbout_Epx2_G3_textIdontCareAbout"
"textIdontCareAbout_Epoxy_105_textIdontCareAbout"]
AllFiles = 4×1 string array
"textIdontCareAbout_Phenolic32_Group5_textIdontCareAbout" "textIdontCareAbout_P1_textIdontCareAbout" "textIdontCareAbout_Epx2_G3_textIdontCareAbout" "textIdontCareAbout_Epoxy_105_textIdontCareAbout"
AllFiles = extractAfter(AllFiles,"_")
AllFiles = 4×1 string array
"Phenolic32_Group5_textIdontCareAbout" "P1_textIdontCareAbout" "Epx2_G3_textIdontCareAbout" "Epoxy_105_textIdontCareAbout"
AllFiles = reverse(extractAfter(reverse(AllFiles),"_"))
AllFiles = 4×1 string array
"Phenolic32_Group5" "P1" "Epx2_G3" "Epoxy_105"
upperchars = isstrprop(AllFiles,'upper')
upperchars = 4×1 cell array
{[1 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 0]} {[ 1 0]} {[ 1 0 0 0 0 1 0]} {[ 1 0 0 0 0 0 0 0 0]}
digitchars = isstrprop(AllFiles,'digit')
digitchars = 4×1 cell array
{[0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 1]} {[ 0 1]} {[ 0 0 0 1 0 0 1]} {[ 0 0 0 0 0 0 1 1 1]}
AllFiles = arrayfun(@(a,b,c)(string(a{1}(find(b{:} | c{:})))),cellstr(AllFiles),upperchars,digitchars)
AllFiles = 4×1 string array
"P32G5" "P1" "E2G3" "E105"
IDK, maybe regexp will be better/easier (I've never been able to get my head wrapped around regular expressions and patterns).
Gabriel Stanley
Gabriel Stanley on 8 Sep 2022
...I feel bad, because in the time you've developed this solution I also managed to develop the appropriate regexp for the Phenolic and Epoxy groups, and am now going figuring our how to fuse the two resulting arrays.

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Accepted Answer

Stephen23
Stephen23 on 8 Sep 2022
S = [...
"textIdontCareAbout_Phenolic32_Group5_textIdontCareAbout"
"textIdontCareAbout_P1_textIdontCareAbout"
"textIdontCareAbout_Epx2_G3_textIdontCareAbout"
"textIdontCareAbout_Epoxy_105_textIdontCareAbout"];
T = regexp(S,'_.+_','match','once');
T = regexprep(T,'[^A-Z\d]','')
T = 4×1 string array
"P32G5" "P1" "E2G3" "E105"
  3 Comments
Stephen23
Stephen23 on 8 Sep 2022
Edited: Stephen23 on 8 Sep 2022
Why are you nesting this character vector in a superfluous scalar cell array?:
SingleExpression = {'(E(poxy|px)?|P(hen(olic)?)?)(_)?\d{1,3}(_G(rp|roup)?(_)?\d{1,2})?'};
"However when trying to run a second invocation of regexp on in resulting array temp, MatLab threw the fault... The solution to the above was the have an intermediate cellstr operation on temp:"
The error occurs because you did not use the ONCE option, as shown in my answer, so your code adds an extra layer of nested cell arrays. Rather than adding extra commands (e.g. CELLSTR) the simple and efficient solution is to specify the ONCE option, just as I showed you:
temp = regexpi(AllFiles,SingleExpression,'match','once')
% ^^^^^^ simply specify this
Gabriel Stanley
Gabriel Stanley on 8 Sep 2022
The cell brackets {} are because I forgot I don't need them for string arrays. And I've taken your direction and added the 'once' option to the regexpi call. Thank you for your help.

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