SELECT SPECIFIC VALUES FROM AN ARRAY

Question

Juan Pablo Guamn Bernal 2020-11-3

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/635124-select-specific-values-from-an-array

评论： Juan Pablo Guamn Bernal 2020-11-9

I have an array with this information from a FEM simulation, I need to build a data base from several iterations on the simulation, nevertheless I am having hard time to get the specific value number, however I was able to build this array where I have the results but I need just the first number number, like 0,78, 47,08, -0,83......1,27, I will really appreciate any hepl, best regards

'   0.78 sec'
'  47.08 oC(116.75 oF)'
'  27.84 oC( 82.10 oF)'
'  -0.83 J/cm2-sec (-5.07e-03 Btu/in2-sec)'
'  -8.86 J/cm2 (-5.42e-02 Btu/in2)'
'   0.44 J/cm2-sec (2.70e-03 Kbtu/in2-sec)'
'   4.71 J/cm2 (2.89e-02 Btu/in2)'
'  25.49 ~ 185.56 oC( 77.87 ~ 366.01 oF)'
'  26.08 ~  30.63 oC( 78.94 ~  87.14 oF)'
'  -5.31 ~   1.00 J/cm2-sec( -0.03 ~   0.01 Btu/in2-sec)'
' -56.74 ~  10.70 J/cm2( -0.35 ~   0.07 Btu/in2)'
'   0.12 ~   2.10 J/cm2-sec(  0.00 ~   0.01 Btu/in2-sec)'
'   1.27 ~  22.49 J/cm2(  0.01 ~   0.14 Btu/in2)'

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Rik 2020-11-3

What did you try already? It helps if you try to come up with the complete list of patterns that the numbers can have. That way you can see if textscan will suffice, or if you need a regular expression (or the new pattern functionality).

Juan Pablo Guamn Bernal 2020-11-9

Thanks for your time, yeah I tried textscan but the outcome was hard to organize

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Answer 1

dpb 2020-11-3

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Presuming from the above you have the cellstr array given, using the simplified string-matching functions, one solution would be something like:

% make a cellstr array from the text...
c={'   0.78 sec'
'  47.08 oC(116.75 oF)'
'  27.84 oC( 82.10 oF)'
'  -0.83 J/cm2-sec (-5.07e-03 Btu/in2-sec)'
'  -8.86 J/cm2 (-5.42e-02 Btu/in2)'
'   0.44 J/cm2-sec (2.70e-03 Kbtu/in2-sec)'
'   4.71 J/cm2 (2.89e-02 Btu/in2)'
'  25.49 ~ 185.56 oC( 77.87 ~ 366.01 oF)'
'  26.08 ~  30.63 oC( 78.94 ~  87.14 oF)'
'  -5.31 ~   1.00 J/cm2-sec( -0.03 ~   0.01 Btu/in2-sec)'
' -56.74 ~  10.70 J/cm2( -0.35 ~   0.07 Btu/in2)'
'   0.12 ~   2.10 J/cm2-sec(  0.00 ~   0.01 Btu/in2-sec)'
'   1.27 ~  22.49 J/cm2(  0.01 ~   0.14 Btu/in2)'};
% the quotes are probably not really there but display of cell string, but just in case 
% and because were in the pasted text to build the array, get rid of them...
c=strrep(c,"'",'');
% extract the first set numeric data
>> data=str2double(extractBefore(strtrim(c),' '))
data =
          0.78
         47.08
         27.84
         -0.83
         -8.86
          0.44
          4.71
         25.49
         26.08
         -5.31
        -56.74
          0.12
          1.27
>>

strtrim removes the leading blanks so can use extractBefore on the blank in the record.

As Rik says, textscan would also work but it's often simpler to use other text processing. regexp is powerful but not needed for the basic problem posed.