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using fscanf to sort x and y values into vectors

Asked by Caitlin Schmidt on 23 Jul 2019
Latest activity Commented on by Walter Roberson
on 30 Jul 2019
I have attached the data file I am referencing. I need to separated the x-values and the y-values into two separate vectors. This is what I have created:
function [x,y]= week8_4_1(filepath)
%This function will read from a data file and extract all x and y data
%values, and put them into vectors
[fid,msg]=fopen(filepath);
if fid==-1
disp(msg);
else
mat=fscanf(fid,'x %f y %f\n',[2,inf]);
x=mat(1,:);
y=mat(2,:);
status=fclose(fid);
if status~=0
disp('File could not be closed');
else
disp('File closed successfully');
end
end
end
I keep getting an error when I try to run the program saying:
Index in position 1 exceeds array bounds.
Error in week8_4_1 (line 11)
x=mat(1,:);
I'm not sure what is wrong with my code. Any help is appreciated!

  5 Comments

You could attach the data file so that we could examine it.
I cannot attach it because it is a .dat file.
See my response on your other question

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1 Answer

Answer by Chidvi Modala on 30 Jul 2019

I see your mat file is empty that could be the reason behind this error. I assume that you are trying to read data from data file by excluding the characters ‘x’, ‘y’ and the data file has data in the below format
x2 y3
x4 y5
Try replacing mat=fscanf(fid,'x %f y %f\n',[2,inf]); with mat = fscanf(fid,[’x’ ‘%f’ ‘ y’ ‘%f\n’],[2 inf]);
You can refer to https://www.mathworks.com/help/matlab/ref/fscanf.html to see how to skip special characters in file using ‘fscanf’.

  1 Comment

I do not see how that change can make any difference. Computing a character vector with [] of static parts that are all character vectors is the same as just hardcoding the complete vector, except hypothetically in cases of errors in the execution engine or JIT

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