Array from CSV File

Hi there,

I have a 4 columns .csv file. I want to create an matrix of only the SECOND And FOURTH columns

How do I do this?

Thanks!

Answer 1

[Walter Roberson]

filename = 'BlackModelTest.csv';
[fid, msg] = fopen(filename, 'rt');
if fid < 0
    error('Could not open file "filename" because: "%s"', filename, msg);
end
col2 = {};
col4 = {};
while true
    thisline = fgetl(fid);
    if ~ischar(thisline); break; end   %normal: indicates end of file
    if isempty(thisline); continue; end  %empty line, including possibly just before end of file
    fields = regexp(thisline, ',', 'split');
    if length(fields) >= 2
       col2{end+1} = fields{2}; 
    end
    if length(fields) >= 4
        col4{end+1} = fields{4};
    end
end
fclose(fid);

temp = str2double(col2);
if ~any(isnan(temp))
    col2 = temp;    %convert to double if ALL entries can be converted
end
temp = str2double(col4);
if ~any(isnan(temp))
    col4 = temp;   %convert to double if ALL entries can be converted
end

You will now have variables col2 and col4. If the columns contained only numeric values, then the corresponding variable will be numeric; otherwise it will be a cell array of character vectors. This code does not try to figure out whether there were header lines.

This code does not assume that all lines are complete or that all lines are the same number of fields. Extra fields will be ignored. If the line is too short then the empty array will be at that location.

[Megan Stapley]

How do I get col2 and col4 into ONE MATRIX?

[Megan Stapley]

All I want to see in my output is this: How do I achieve that? None of your solutions have worked thus far.

[Walter Roberson]

{col2(:), col4(:)}

[Megan Stapley]

Didn't work...output:

final =

1×2 cell array

{21×1 cell} {21×1 cell}

[Walter Roberson]

[col2, col4]

[Megan Stapley]

That outputs a 1 X 42 array

Not a 2 column matrix

[Walter Roberson]

[col2(:), col4(:)]