importfile regexp thousands separator returns NaN when negative

Question

Craig Cowled 2019-7-17

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评论： madhan ravi 2019-7-17

I used "Import Data" to generate a function importfile for importing a csv file. Unfortunately, the function returns NaN for every number less than or equal to -1,000.

When I step through the generated code, I discover that the error happens in the following code:

            % Detected commas in non-thousand locations.
            invalidThousandsSeparator = false;
            if numbers.contains(',')
                thousandsRegExp = '^\d+?(\,\d{3})*\.{0,1}\d*$';
                if isempty(regexp(numbers, thousandsRegExp, 'once'))
                    numbers = NaN;
                    invalidThousandsSeparator = true;
                end
            end

Let's say that:

numbers = "-1,167.67627";

Then:

regexp(numbers, thousandsRegExp, 'once')
ans =
     []

Hence, the code returns a NaN when it should be giving me a number of -1167.67627.

Compare this to the result when the number is positive:

 numbers = "1,167.67627";
 regexp(numbers, thousandsRegExp, 'once')
 ans =
       1

Obviously, the error comes from the following code, but I have no idea how to fix this 'matched regular expression':

thousandsRegExp = '^\d+?(\,\d{3})*\.{0,1}\d*$';

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Answer 1

madhan ravi 2019-7-17

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https://ww2.mathworks.cn/matlabcentral/answers/472073-importfile-regexp-thousands-separator-returns-nan-when-negative#answer_383507

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str2double(regexprep(numbers,',',''))

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Craig Cowled 2019-7-17

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Thank you, madhan ravi. Something very similar is in the next section of code:

            % Convert numeric text to numbers.
            if ~invalidThousandsSeparator
                numbers = textscan(char(strrep(numbers, ',', '')), '%f');
                numericData(row, col) = numbers{1};
                raw{row, col} = numbers{1};
            end