MATLAB Answers


Trouble using sscanf to find numbers in a string?

Asked by Olivia Colombo on 20 Feb 2019
Latest activity Commented on by Akira Agata
on 20 Feb 2019
I'm new to using sscanf, and I'm trying to find the numbers within sentences that contain a temperature. Where it finds an F it converts the temp to celsius, then puts all the temperatures in a new array. The file is attached below. Thanks!

  1 Comment

Could you upload TemperatureRecord.txt to test your code?

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1 Answer

Answer by Akira Agata
on 20 Feb 2019
Edited by Akira Agata
on 20 Feb 2019

Thank you for uploading your data file!
How about the following?
% Read data file
fid = fopen('TemperatureRecord.txt','r');
s = textscan(fid,'%s','Delimiter','\r\n');
s = s{1};
% Remove leading and trailing space from each line
s = strip(s);
% Remove final ./!/?, if line ends with one of them
s = regexprep(s,'(\.|\!|\?)$','');
% Index where sentence ends with F/f/Fahrenheit/fahrenheit
idxF = endsWith(s,{'F','f','Fahrenheit','fahrenheit'});
% Extract number only
A = regexp(s,'[0-9\.]+','match');
% Convert to doulbe
A = cellfun(@str2double,A);
% Convert F to C
A(idxF) = (A(idxF) - 32)*(5/9);


This will not work on linux (or on many files written by applications on Windows that do not insert useless carriage returns). Two simple adjustments make this work for all OS and all files:
fid = fopen('TemperatureRecord.txt','rt'); % rt
s = textscan(fid,'%s','Delimiter','\n'); % \n
s = s{1};
Hi Stephen-san,
Oh, I have been assuming running it on Windows, only.
Thank you for your useful comment!

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