How to do the example below in MatLab? I am dealing with same sort of problem in matlab

Question

muhammad choudhry 2022-6-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1742185-how-to-do-the-example-below-in-matlab-i-am-dealing-with-same-sort-of-problem-in-matlab

评论： Les Beckham 2022-6-17

采纳的回答： Les Beckham

Problem:

i have 3 csv files named file1, file2, file3. Each CSV is filled with 3 Columns and 5653 rows:

1 0 -95

2 0 -94

3 0 -93

...

51 0 -93

0 1 -92

1 1 -91

2 1 -90

First column is a X variable 2nd is a y variable, 3rd is a measured value from which I want to have the mean.

What I want to do is:

read first row of file 1
read first row of file 2
read first row of file 3 and then count the mean of the measured value.

So for example:

file1 row1 -98

file2 row1 -97

file3 row1 -95

mean 96,666666667

i want to write that mean into a new csv file with the following format

1,0,mean_of_row1 (which would be 96,666666667)

2,0,mean_of_row2

3,0,mean_of_row3

4,0,mean_of_row4

Solution in Python:

import pandas as pd

df1=pd.read_csv('file1.txt',names=['x1','Y1','Value1'],nrows=5356)

df2=pd.read_csv('file2.txt',names=['x2','Y2','Value2'],nrows=5356)

df3=pd.read_csv('text3.txt',names=['x3','Y3','Value3'],nrows=5356)

df_concat= pd.concat([df1,df2,df3], axis=1)

print df_concat

df_concat['meanvalue']=df_concat[['Value1','Value2','Value3']].mean(axis=1)

print(df_concat.to_csv(columns=['meanvalue'],index=False))

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Answer 1

Les Beckham 2022-6-17

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1742185-how-to-do-the-example-below-in-matlab-i-am-dealing-with-same-sort-of-problem-in-matlab#answer_987320

编辑：Les Beckham 2022-6-17

Something like this should do what you want (using made up example data):

% simulating read of csv file1 (replace by data1 = readmatrix('file1.csv')
data1 = ...
    [1   0   -98
     2   0   -94
     3   0   -93];
% simulating read of csv file2 (replace by data2 = readmatrix('file2.csv')
data2 = ...
    [1   0   -97
     2   0   -95
     3   0   -92];
% simulating read of csv file3 (replace by data3 = readmatrix('file3.csv')
data3 = ...
    [1   0   -95
     2   0   -93
     3   0   -91];
% calculate the means of the third column of each of these datasets
mean_data = mean([data1(:,3) data2(:,3) data3(:,3)], 2)
mean_data = 3×1
  -96.6667
  -94.0000
  -92.0000
output = [(1:numel(mean_data))' zeros(size(mean_data)) mean_data]
output = 3×3
    1.0000         0  -96.6667
    2.0000         0  -94.0000
    3.0000         0  -92.0000
% then use writematrix to create your output file:
%   writematrix(output, 'meandata.csv')

If this doesn't provide the help you need and you have code that you created that is not working and have a specific problem with it, please post it (as text, not as a screenshot) and explain what the problem is. If you are getting an error message, post the entire error message (all of the red text)

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muhammad choudhry 2022-6-17

I have tried the code in the link below, if you can answer that be great. I also explained what I want from the code and what is happening through the code.

https://uk.mathworks.com/matlabcentral/answers/1742180-how-to-take-the-each-row-value-from-50-csv-files-and-take-a-mean-of-it-and-save-into-different-file?s_tid=srchtitle

Les Beckham 2022-6-17

You need to collect up all of the desired columns inside the loop and then take the mean after the loop.

Here is an example.

% Create the test data
data1 = ...
    [1   0   -98
     2   0   -94
     3   0   -93];
writematrix(data1, 'file1.csv');
data2 = ...
    [1   0   -97
     2   0   -95
     3   0   -92];
writematrix(data2, 'file2.csv');
data3 = ...
    [1   0   -95
     2   0   -93
     3   0   -91];
writematrix(data3, 'file3.csv');
data4 = ...
    [1   0   -95
     2   0   -93
     3   0   -91];
writematrix(data4, 'file4.csv');
clearvars % clear the variables so we can read it from the files
% Now read the files and do the calculations
files = dir('*.csv');
numrows = 3; % in your case it would be 48
numfiles = numel(files); % in this example 4, in your case 79
col3 = zeros(numrows, numfiles); % container for all of the column 3 data (in your case, column 13)
for i=1:numfiles
    data = readmatrix(fullfile(files(i).folder, files(i).name));
    col3(:,i) = data(:,3); % extract the desired column
end
% calculate the means of the third column of each of these datasets
mean_data = mean(col3, 2)
mean_data = 3×1
  -96.2500
  -93.7500
  -91.7500
output = [(1:numel(mean_data))' zeros(size(mean_data)) mean_data] % create output array (modify to your desired format)
output = 3×3
    1.0000         0  -96.2500
    2.0000         0  -93.7500
    3.0000         0  -91.7500
% then use writematrix to create your output file:
%   writematrix(output, 'meandata.csv')