How to use FIND function here?

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Chathu 2015-2-13

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/178029-how-to-use-find-function-here

编辑： per isakson 2015-2-25

I need to find the very first corresponding value of the payload when time is 0.0000.

Next,find the corresponding value of payload when time is 1.000.Likewise when time is 2.0000 and time is 3.0000. (pls note that payload column needs to convert to decimal values) [file is attached, herewith]

below is the code i used so far:

    clc
    clear all
    fid=fopen('test.txt');
    data=textscan(fid, '%*d%f%*s%*s%*s%*d%s', 40 ...
                , 'MultipleDelimsAsOne',true, 'HeaderLines',1);
    fclose(fid);
    S=hex2dec(data{:,7});

Any suggestions?

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per isakson 2015-2-13

"corresponding value of payload when time is 1.000." &nbsp closest to 1 or by integration or what does "corresponding" mean?

Chathu 2015-2-13

在 MATLAB Online 中打开

@ per isakson- oh...sorry for the confusion.

 time        payload       converted value(used hex2dec fun for the payload col)
0.0000      03ff00000166  2.1518*1.0e+12
.           .....         ........
.           .....         .......
1.0993      03ff00000171  2.1518*1.0e+12
.           .....         ....
.           ....          ....
2.0974      01f60000011a  2.1561*1.0e+12

Here, what i meant was: i need to get 1st and 3rd column as my output. Any idea how to solve it?

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Answer 1

per isakson 2015-2-13

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/178029-how-to-use-find-function-here#answer_167854

编辑：per isakson 2015-2-25

在 MATLAB Online 中打开

"I need to get 1st and 3rd column as my output." &nbsp Is this what you want?

    fid=fopen('test.txt');
    data=textscan(fid, '%*d%f%*s%*s%*s%*d%s', 40 ...
                , 'MultipleDelimsAsOne',true, 'HeaderLines',1);
    fclose(fid);
    S = hex2dec(data{2});
    my_output = cat( 2, data{1}, S );
    >> whos my_output
      Name            Size            Bytes  Class     Attributes
      my_output      40x2               640  double

"How to use FIND function here?" &nbsp I cannot see how find could be used here.

&nbsp

Addendum with inputs from the comments

Add the following lines to the script above.

    sbs = floor(my_output(:,1)) + 1;
    val = accumarray( sbs, my_output(:,2), [], @mean );
    t1  = accumarray( sbs, my_output(:,1), [], @min  );
    t2  = accumarray( sbs, my_output(:,1), [], @max  );
    out = [ t1, t2, val ]; 
    fprintf( '%g, %g, %g\n', transpose( out ) )

The script will now output

    0, 0.998058, 4.39375e+12
09832, 1.99722, 4.39375e+12
09746, 2.99636, 4.39375e+12
09557, 3.89427, 4.39375e+12

&nbsp

A second addendum with inputs from the comments

Replace

val = accumarray( sbs, my_output(:,2), [], @mean );

by

    first_value = @(vec) vec(1);
    val = accumarray( sbs, my_output(:,2), [], first_value );

to get "very first corresponding value of the payload".

From testing and the documentation I understand that accumarray does not keep the order of the input values.

Correction: "does not keep" should be "does keep". If not, the function, first_value would be useless.

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per isakson 2015-2-21

In the original question you say "find the very first corresponding value". I had forgotten that when I wrote @mean. Does "real values" refer to this "first [...] value"?

Chathu 2015-2-25

@ per isakson- Just now saw this message. Thanks ALOT for your response. It is very kind of you to reply me even after accepting your answer. Your genuine support is truly admired. Yes, with your help i managed to solve my qu. Keep up the good work. Thanks!

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