How to read in a lot of files, average a column, and output in a new file?

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amcgough
amcgough 2017-7-19
评论： Ayesha Batool 2020-1-27
Hi, I want to read in a bunch of different .csv files from a folder, average the 8th column of each individual one, and then output the averages into a new .csv file as a single column list. I have tried some code so far, but I cannot figure out how to apply it to multiple files in a folder rather than just reading in one file.
M = csvread()
average = mean(M(:,8));
csvwrite('output.csv',average);
I also read to do something like this to read in multiple files but I'm not sure how to integrate these two chunks of code.
csvFiles = dir('*.csv');
numfiles = length(csvFiles);
mydata = cell(1, numfiles);
for k = 1:numfiles
mydata{k} = imread(csvFiles(k).name);
end
Thanks for your help, I'm pretty new to Matlab so please bear with me :)

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回答（2 个）

Jan
Jan 2017-7-19
folder = 'C:\Your\Folder\';
csvFiles = dir(fullfile(folder, '*.csv')); % Use absolute path names
numfiles = length(csvFiles);
average = zeros(1, numfiles);
for k = 1:numfiles
M = csvread(fullfile(folder, csvFiles(k).name));
average(k) = mean(M(:,8));
end
csvwrite(fullfile(folder, 'output.csv'), average);
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Jan
Jan 2017-7-19
If "csvread adds 1,2 at the end" means, that the arguments "1, 2" are appended to the inputs of csvread, simply do this: Replace
M = csvread(fullfile(folder, csvFiles(k).name));
by
M = csvread(fullfile(folder, csvFiles(k).name), 1, 2);
Ayesha Batool
Ayesha Batool 2020-1-27
Hi Jan
my current folder in is
participant_folders = dir('D:\PhD\Research\Experimental Design\Experiment 1\DATA\Analysis\Nystrom');
I want the code to read each folder in folder_in but not the files in it, instead read two folders in, 100514\detectectionrecults\ then read the csv file ending in 'Fixaduration.csv' and output a file csv with an average.
If I want to access this folder D:\PhD\Research\Experimental Design\Experiment 1\DATA\Analysis\Nystrom\100514\DetectionResults\1_1\averages
it takes up the list of csv and outputs the average in a csv.
However I want to automate the algorithm to go through hundreds of folders and output one average for a file ending in a certain name.
the file path way is If I want to access this folder D:\PhD\Research\Experimental Design\Experiment 1\DATA\Analysis\Nystrom\100514\DetectionResults\1_1\averages\1_1_FixationDuration.csv
This is working for one folder:
folder = 'D:\PhD\Research\Experimental Design\Experiment 1\DATA\Analysis\Nystrom\100514\DetectionResults\1_1\averages\';
csvFiles = dir(fullfile(folder, '*.csv')); % Use absolute path names
numfiles = length(csvFiles);
average = zeros(1, numfiles);
for k = 1:numfiles
M = csvread(fullfile(folder, csvFiles(k).name));
average(k) = mean(M(:,1));
end
csvwrite(fullfile(folder_out, 'output.csv'), average);
but
I'm trying to write it for all participants:
participant_folders = dir('D:\PhD\Research\Experimental Design\Experiment 1\DATA\Analysis\Nystrom');
isub = [participant_folders(:).isdir]; %# returns logical vector
nameFolds = {participant_folders(isub).name}';
nameFolds(ismember(nameFolds,{'.','..'})) = [];
for participant = 1:size(nameFolds,1)
folder_in = ['D:\PhD\Research\Experimental Design\Experiment 1\DATA\Analysis\Nystrom\',...
nameFolds{participant},'\'];
files = dir([folder_in, '*.csv']);
for f = 1:size(files,1)

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Angana Borah
Angana Borah 2019-9-9
What if I want find the average of only a few files from that directory, instead of the fullfile, whose ".name" I know?

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