Import data from text sheet to a variable

I have an text file with following entries

    id    pid    sigma   temp  value   dist
    12    369   1740    528    187       9.01
    19    741    730    519    206       9.1
    13    405   1003    467    158      10.10
    32   2179    419    445    191      11.1
    18    721    397    657    120      13.2
    22   1478    365    600    304      13.3
    41   2520   1180    526    179      13.41

i only want to import the dist value to a variable

i.e i want to have my variable

x = [9.01 9.1 10.10 11.1 13.2 13.3 13.41]

Is there a way I could only the 6th column entries from text file to matlab variable x.

Answer 1

[Azzi Abdelmalek]

fid = fopen('file.txt')
data = textscan(fid, '%*s %*s  %*s %*s %*s %f %*[^\n]','HeaderLines',1);
fid = fclose(fid);

[Image Analyst]

And then finally:

% Convert cell to nummerical array then transpose into row vector.
x = cell2mat(data)'

[Walter Roberson]

An amplifying remark: when you use text files, it is necessary to read all of the content of the line, but parts can be thrown away without being returned. It is not possible to read just a column in text files. This is a limitation on text files.

The exception to this would be if the text file lines are all exactly the same size and you are not using \r\n line terminators. In such a case once you have read a column on one line you could fseek() forward by the fixed number of characters to reach the beginning of the column in the next line. Some low level routine might still end up reading those characters in-between but that would be a "quality of implementation" matter. If you are using \r\n line terminators then you can probably get it to work with fseek() but the official rules say that you aren't supposed to do it in the case of "text" files (the newline only case can be treated as a binary file within the rules.)

[Navya Snigdha Thumma]

Try this

x=dlmread('your datafile name','',1,5);

if your dataset delimiter is tab use '\t' instead if ''

It basically reads your data like matrix [00 01 02 03 04 05; 10 11 12 33........] and if specified it starts reading the block from given number till the end.

[Walter Roberson]

Navya, unfortunately dlmread() cannot be used for files which contain any text at all, even if the row and columns requested are after where the text is.

dlmread() uses an undocumented feature of textscan() that only works when the columns are purely numeric.

In the cases that dlmread() does work for, it is a matter of the code reading and converting the values first, and then throwing away the parts that are not wanted. As I describe above, it is not possible to read only the desired column, that everything must be read for text files, but the other parts can be discarded.

[santosh v]

@navya: thanks for the link.. it worked for my case!