HOW TO READ DATA FROM 4 TEXT FILES SIMULTANEOUSLY LINE BY LINE AND FIND THE MEDIAN OF EACH LINE ?

i have got 4 .txt files which represents the data at 4 different times in a day, which iam attaching below. And i have to write a program such that it start reading from 17th line(after the heading pressure) in all the 4 files simulatenously. The secondlast column in all the file specifies the height and i have to find its median. so what i finally get should be the median of the height(second last colmn in each file) These 4 files should be calculated together. (For example : when these 4 files are placed sidebyside, we get 4 height data on the 17th line itself. find the median of these 4 data ..like that)

This process has to be repeated for the entire lines of the file.So finally we get about more than 500 median value. Can u pls help me write a code for this task? Iam new to matlab and have very little programming skill. ANY HELP WOULD BE MUCH APPRECIATED.PLS

Answer 1

[Rik]

This code should do the trick:

fnames={'1OCT3AM.txt','1OCT6AM.txt','1OCT9AM.txt','1OCT12AM.txt'};
lastcol=zeros(1,numel(fnames));
n_lines_skip=16;
FormatSpec='%d %d %d %d %d %d %d %d %f %f %f %f %f';

for n_file=1:numel(fnames)
    fid=fopen(fnames{n_file},'r');
    c=textscan(fid,FormatSpec,'HeaderLines',n_lines_skip);
    lastcol(1:numel(c{end}),n_file)=c{end};
    fclose(fid);
end
median_values=median(lastcol,2);

[lakshmi dwaraka]

Thankyou for replaying. But the median seems to be wrong. The height data value (secondlast column) is 500. 4 files i provided had the data value 500. So the median will be 500. But as per this code. the answer i get is 952.55. There is something wrong.

[Rik]

I misread your question, I thought you needed the last column, not the second to last.

k=1;
data(1:numel(c{end-k}),n_file)=c{end-k};

Now data will contain the values from the k-to-last column.

[lakshmi dwaraka]

Thankyou so much. I also need the medians of third column from the last( represents the longitude) as well as the median of the forth column from the last (representing latitudes) too.Sothese 3 medians should be 3 columns ultimately. Can u pls modify the above code and help me?

[Rik]

The modification you are asking for are really basic operations. Why don't you try to learn using the tool you are working with? Any tutorial should teach you how to do this.

[lakshmi dwaraka]

The loop i gave seems to overwrite the median_values. so only the last iteration value is getting as output.

Thanks for the help!

[Rik]

Glad to be of help. If my answer solved your question, please click the 'accept answer' button.