Select last numeric character(s) of the string

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Aleksandra Budzinska
评论： Dyuman Joshi 2023-4-26
Hello,
I'm hoping for an advise on the code which has to do with extracting the digits (either 1,2 or 3) from the string which includes different condition names. It's about a rating from -100 to 100 given to different conditions.
In our other script the output gave the ratings saves as: e.g "sucrose: 10". Now it's: e.g. "sucrose10".
How can I extract the last numbers occurring at the end of different strings? I'll provide the code we had below to deal with the separation using ":" which now doesn't work.
log.rating = zeros(height(log),1);
for l = 1:height(log)
if contains(char(log.Code(l)),'score','IgnoreCase',true)
scorestring = char(log.Code(l));
if strcmp(scorestring(end-3:end),'-100')
log.rating(l) = str2double(str(scorestring(end-3:end)));
elseif ~contains(scorestring(end-2:end))
log.rating(l) = str2double(str(scorestring(end-2:end)));
else
log.rating(l) = str2double(str(scorestring(end-1:end)));
end
else
log.rating(l) = NaN;
end
end
Many thanks!!
  1 个评论
Aleksandra Budzinska
Aleksandra Budzinska 2023-4-25
The example strings are: 'Sucrose low10','Sucrose high-100','Erythritol high5','Erythritol low-10', 'Control0'

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采纳的回答

Stephen23
Stephen23 2023-4-25
编辑：Stephen23 2023-4-25
Ran in:
"How can I extract the last numbers occurring at the end of different strings?"
X = "sucrose-10";
Y = str2double(regexp(X,'[-+]?\d{1,3}$','match','once'))
Y = -10
This replaces your innermost IF-ELSEIF-ELSE-END. You could probably use it to replace you entire FOR loop too.
It detects from 1 to 3 digits at the end of the text.
It will also detect an optional +/- sign in front of those digits.
See also:
https://www.mathworks.com/help/matlab/matlab_prog/regular-expressions.html
https://www.mathworks.com/matlabcentral/fileexchange/48930-interactive-regular-expression-tool
  2 个评论
Stephen23
Stephen23 2023-4-25
编辑：Stephen23 2023-4-25
Ran in:
Assuming that LOG is a table (you did not explain this in your question):
log = array2table(["scoreABC-23";"DEF 100";"scoreGHI-100";"JKLscore: 99"], 'VariableNames',{'Code'})
log = 4×1 table
Code ______________ "scoreABC-23" "DEF 100" "scoreGHI-100" "JKLscore: 99"
idx = contains(log.Code,'score','IgnoreCase',true);
log.Rating = nan(size(log.Code));
log.Rating(idx) = str2double(regexp(log.Code(idx),'[-+]?\d{1,3}$','match','once'))
log = 4×2 table
Code Rating ______________ ______ "scoreABC-23" -23 "DEF 100" NaN "scoreGHI-100" -100 "JKLscore: 99" 99
Don't fight MATLAB with loops and IFs. Think in terms of vectors and matrices.
Aleksandra Budzinska
Aleksandra Budzinska 2023-4-25
Dear @Stephen23 the first sugegstion worked very well and indeed I got rid of the IF-ELSEIF-ELSE-END parts. Thank you very much!!

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更多回答（1 个）

Kevin Holly
Kevin Holly 2023-4-25
Ran in:
output = 'sucrose: 10';
numbers = str2double(extract(output, digitsPattern))
numbers = 10
output = "sucrose10";
numbers = str2double(extract(output, digitsPattern))
numbers = 10
  2 个评论
Aleksandra Budzinska
Aleksandra Budzinska 2023-4-25
Dear Kevin,
Thanks for your quick reaction although I don't understand the difference between your first and second code.
I was trying to use for all the possible lengths of the digits we might have but it doesn't work properly:
if strcmp(scorestring(end-3:end),'-100')
log.rating(l) = str2double(extract(scorestring(end-3:end)));
elseif ~contains(scorestring(end-2:end))
log.rating(l) = str2double(extract(scorestring(end-2:end)));
else
log.rating(l) = str2double(extract(scorestring(end-1:end)));
Dyuman Joshi
Dyuman Joshi 2023-4-26
Ran in:
"although I don't understand the difference between your first and second code. "
@Aleksandra Budzinska, they are the same code, Kevin just used two different inputs to show the result.
However, @Kevin Holly, this fails to include the negative sign for negative numbers -
output = 'Sucrose high-100';
numbers = str2double(extract(output, digitsPattern))
numbers = 100

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