Aggregating the same value data and finding the average

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test1.csv

I read data from a CSV file. The file contains data values which has the same value in the first column. I use the following code to read the vales. However the if condition is not working after three iterations.

%start = 20659200000.000000;
Array=csvread('test1.csv');
format long g;
start = 20659200000.000000;
%start = 2.06592e+10
d = size(Array, 1);
dd = 0;
i = 1;
while i < d
  tmp = Array(i,1);
%      start = 20659200000.000400;
  if eq(tmp , start)
       start = start + 0.000100;
        dd = dd + 1;
       PArray(i,1)= Array(i,1);
       PArray(i,2)= Array(i,2);
    end
i = i + 1;
end

I have attached the test file I use too. Can anybody sport what is the bug in the if condition?

Thanks in advance

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blackhawk 2015-1-19

Yes like per isakson mentioned I have overlooked the Attach File button. It is now attached. Sorry this is the first time I user this forum

blackhawk 2015-1-19

编辑：blackhawk 2015-1-19

I tried this too, still it won't iterate more than 3

value = tmp - start; if eq(value,0)

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Answer 1

Image Analyst 2015-1-19

在 MATLAB Online 中打开

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Tons of errors in the code, the main error being that you're comparing floating point numbers for equality and you're not following the FAQ: http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F Attached is the fixed code:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
Array=csvread('test1.csv');
start = 20659200000.000000;
tolerance = 0.01;
rows = size(Array, 1)
equalityCount = 0;
for row = 1 : rows;
  tmp = Array(row,1);
  fprintf('In row #%d of %d, column 1 = %f\n', row, rows, tmp);
  if abs(tmp - start) < tolerance
    start = start + 0.000100;
    equalityCount = equalityCount + 1;
    PArray(row,1)= Array(row,1);
    PArray(row,2)= Array(row,2);    
    fprintf('^^^ Row %d above has equality ^^^\n', row);
  end  
end
fprintf('EqualityCount = %d\n = %.1f%%of the rows.\n', equalityCount, 100*equalityCount/rows);
msgbox('Done with demo');

It could be better and more robust, but it at least works now. Adjust the tolerance to what you want/need.

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blackhawk 2015-1-19

Thank you Image Analyst for the floating point number pointer and fixing the issues in the code. Your code works, however looking at the PArray there are many zero values. What could be the reason? Finally I want to plot the PArray.

plot(PArray(:, 1), PArray(:, 2));

Image Analyst 2015-1-19

PArray does not get any values unless the value is within tolerance of the start value, so many go unassigned and remain zero.

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Aggregating the same value data and finding the average

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