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

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muhammad choudhry
muhammad choudhry 2022-6-16
评论： Les Beckham 2022-6-17
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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Les Beckham
Les Beckham 2022-6-17
编辑：Les Beckham 2022-6-17
Ran in:
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)
  2 个评论
Les Beckham
Les Beckham 2022-6-17
Ran in:
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')

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