Extract float from a filename

Question

K3iTH 2022-2-24

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https://ww2.mathworks.cn/matlabcentral/answers/1657300-extract-float-from-a-filename

评论： K3iTH 2022-2-24

Hi all,

I have a list of files in a directory with a name of "time_ xx" where xx is number (for e.g 0.20, 0.41, 0.61, 0.82,...) the number is not does not have a fixed expression. I want like to extract these number and used it for calculation later.

May I know what function can I used to extract the number from a filename without extension?

Thank you.

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Answer 1

DGM 2022-2-24

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https://ww2.mathworks.cn/matlabcentral/answers/1657300-extract-float-from-a-filename#answer_903310

编辑：DGM 2022-2-24

在 MATLAB Online 中打开

Well I guess this is one way. There are probably more elegant ways of unpacking the nested cell array and converting to numeric, but this is how I did it.

names = {'time_0.709'
    'time_5.61'
    'time_0.2081'
    'time_45.027'
    'time_90'};
filenums = str2double(regexprep(names,'.*_(?=(\d*\.*)+$)',''))
filenums = 5×1
    0.7090
    5.6100
    0.2081
   45.0270
   90.0000

This looks for any number between an underscore and the end of each name. The filename prefix is ignored except for the underscore.

I guess if you wanted rely on the prefix, you could alternatively just do:

names = {'time_0.709'
    'time_5.61'
    'time_0.2081'
    'time_45.027'
    'time_90'};
filenums = str2double(strrep(names,'time_',''))
filenums = 5×1
    0.7090
    5.6100
    0.2081
   45.0270
   90.0000