str2num sending figures to printer, is there an alternative?

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Jan
Jan 2024-3-26
评论： Jan 2024-3-26
While parsing a long text file using the STR2NUM command (to extract only numerical values from the file), matlab sent many empty FIGs to the printer for printing. It even used all the papers in the printer! Funny morning. I am aware of the option: Evaluation='restricted', yet it was unexpected.
What happened was that in the text file there was a line of text starting with the word PRINT.
example:
x = str2num('print "Termalization done." append info.txt')
Is there an alternative for simple parsing of text files?
  2 个评论
Dyuman Joshi
Dyuman Joshi 2024-3-26
编辑：Dyuman Joshi 2024-3-26
"to extract only numerical values from the file"
Why are you using str2num for that?
Read the data by using appropriate function e.g. - textscan, fscanf, fileread paired with regexp etc, as per how the data is formatted/structured.
Jan
Jan 2024-3-26
The textfile format is not fixed and a line of numbers was expected following specific pattenrs. Thus for converting a line of text with a few numbers to reals (vector) the command str2num was a direct option for me. I did not expect my printer to print while converting a string to reals. TEXTSCAN seems like a perfect option. Thank you.

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回答（1 个）

Hassaan
Hassaan 2024-3-26
编辑：Hassaan 2024-3-26
Ran in:
% Example text line that might be read from your file
textLine = 'The result is 42 and not 43.5 or any other number like -1.23e4';
% Regular expression to match numbers (including decimals and exponentials)
% This pattern matches:
% - Optional sign (+/-)
% - A digit sequence
% - Optional decimal part
% - Optional exponential part (e.g., e+10, e-10)
pattern = '[-+]?\d+\.?\d*(e[-+]?\d+)?';
% Extract matching strings (numbers in this case)
numbersAsStrings = regexp(textLine, pattern, 'match');
% Convert extracted strings to numbers
numbers = str2double(numbersAsStrings);
% Display the extracted numbers
format longG; % This sets the format to long with no trailing zeros
disp(numbers);
42 43.5 -12300
-----------------------------------------------------------------------------------------------------------------------------------------------------
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