How to access substrings out of cell array with indexing?

3 次查看（过去 30 天）
Osvald Ljungstrand
Osvald Ljungstrand 2016-12-20
评论： Osvald Ljungstrand 2016-12-21
Hi all, I searched a lot through the community as there was normally someone with a similar problem. But this time I was not able to find a solution.
I have a cell array (over 13,000x1) with strings and need to extract the number within. Example:
message = { 'error(1): occured due to A' ; ...
'error(25): occured due to B' ; ...
'error(306): occured due to C' };
With 'regexp' I can identify the position of the number:
[a,e] = regexp(message,'\(\d*\)');
Normally I prefer logical indexing but couldn't find a nice solution to access the substrings within a cell array. So for this small array I can extract the number with a loop
number = zeros(size(message,1),1);
for i=1:size(message,1)
number(i) = str2double(message{i}(a{i}+1:e{i}-1));
end
But the for-loop is very time consuming for big cell arrays. I would prefer to use the existing a and e array.
Does anyone has a better way to access substrings within cell arrays?

请先登录，再回答此问题。

采纳的回答

Andrei Bobrov
Andrei Bobrov 2016-12-20
message = { 'error(1): occured due to A' ; ...
'error(25): occured due to B' ; ...
'error(306): occured due to C' }
a = regexp(message,'\d+','match','once')
out = str2double(a)

更多回答（1 个）

David Barry
David Barry 2016-12-20
If you are using R2016b then you can make use of the new String datatype and then use the extractBetween function. This should be very quick.
message = { 'error(1): occured due to A' ; ...
'error(25): occured due to B' ; ...
'error(306): occured due to C' };
message = string(message);
nums = extractBetween(message, '(', ')');
nums = str2double(nums);
  2 个评论
Osvald Ljungstrand
Osvald Ljungstrand 2016-12-21
Nonehteless my "message" looks a bit more complex and I can't just copy paste your suggestion, the combination of the 'match' option for regexp with the extractBetween function will solve my problem perfectly. Thank you a lot for your help

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Characters and Strings 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by