extract data from string

Question

Jes 2022-4-30

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1708905-extract-data-from-string

编辑： dpb 2022-4-30

'%R1P,0,0:0,0.452743429299473,0.000005129603507,0.0000002,0,0.000002,0,0,25899036'

How could I extract the 4th,5th,10th and 11th data from this string to a matrix?

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Answer 1

Voss 2022-4-30

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https://ww2.mathworks.cn/matlabcentral/answers/1708905-extract-data-from-string#answer_954515

在 MATLAB Online 中打开

Maybe something like this:

str = '%R1P,0,0:0,0.452743429299473,0.000005129603507,0.0000002,0,0.000002,0,0,25899036';
% split str on commas into a cell array:
c = strsplit(str,',')
c = 1×11 cell array
    {'%R1P'}    {'0'}    {'0:0'}    {'0.452743429299473'}    {'0.000005129603507'}    {'0.0000002'}    {'0'}    {'0.000002'}    {'0'}    {'0'}    {'25899036'}
% convert elements [4 5 10 11] to numeric:
m = str2double(c([4 5 10 11]));
% display elements of m separately:
format long
for ii = 1:numel(m)
    disp(m(ii));
end
   0.452743429299473

     5.129603507000000e-06

     0

    25899036

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Jes 2022-4-30

hw to chnge the headings

Voss 2022-4-30

在 MATLAB Online 中打开

One way is to type them out:

headings = {'No' 'whatever' 'they' 'should' 'be'};

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Answer 2

dpb 2022-4-30

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https://ww2.mathworks.cn/matlabcentral/answers/1708905-extract-data-from-string#answer_954520

编辑：dpb 2022-4-30

在 MATLAB Online 中打开

The dead-ahead approach...

>> tok=split(s,',');
>> str2double(tok([4:5 10:11]))
ans =
      0.45274
   5.1296e-06
            0
   2.5899e+07
>> 

A different solution to the second Q? would be more like

VARS=[4 5 10 11];                   % the wanted variables
tok=strsplit(s,',');
vNames=compose('Var%02d',1:numel(VARS));
tData=array2table(str2double(tok(VARS)),'VariableNames',vNames);

The results of the last plus how to change names example are:

>> tData=array2table(str2double(tok(VARS)),'VariableNames',vNames)
tData =
  1×4 table
     Var01       Var02       Var03      Var04   
    _______    __________    _____    __________
    0.45274    5.1296e-06      0      2.5899e+07
>> tData.Properties.VariableNames(2)={'MyNewName'}
tData =
  1×4 table
     Var01     MyNewName     Var03      Var04   
    _______    __________    _____    __________
    0.45274    5.1296e-06      0      2.5899e+07
>> 

This takes advantage that the table has the facility for variable names built into the class as an integral part of the class instead of confusing data and the title into a single variable from which it always has to be extracted in order to use the data in the array....and, it allows the data to be of any type whereas adding a variable name for a numeric array requires that the whole array then be a cell array to hold the disparate data types.