diary file_io.out

% Working on file data.  file_io.data is a file of
% more or less random data.

load 'file_io.data'
file_io

file_io =

    4.5000    8.0000    3.0000         0
    6.8000    7.0000    3.0000         0
   10.5000    6.0000    6.0000    1.0000
   15.5000    3.0000    6.0000    1.0000
   16.0000    4.0000    6.0000    2.0000
   18.9000    2.0000    6.0000    2.0000
   23.5000   -1.0000         0    2.0000
   33.6000   -5.0000         0    3.0000
   34.8000   -5.0000         0    3.0000

x = file_io;

% Get the basic statistics
mean (x)

ans =

   18.2333    2.1111    3.3333    1.5556

var (x)

ans =

  116.2950   23.6111    7.7500    1.2778

std (x)

ans =

   10.7840    4.8591    2.7839    1.1304

% Make a new matrix for variables 1 and 4

y=[x(:,1) x(:,4)]

y =

    4.5000         0
    6.8000         0
   10.5000    1.0000
   15.5000    1.0000
   16.0000    2.0000
   18.9000    2.0000
   23.5000    2.0000
   33.6000    3.0000
   34.8000    3.0000

% plot y the simplest possible way.

plot (y)

% plot the two variables in y with a cyan dotted line and a plus at each point

plot (y,'c:+')

% plot the variables against each other. Green line with  circles.

plot (y (:,1), y (:,2),'go')

% Get the covariance matrix

cov (x)

ans =

  116.2950  -52.1292  -18.4625   11.5917
  -52.1292   23.6111    8.9583   -5.0694
  -18.4625    8.9583    7.7500   -1.3333
   11.5917   -5.0694   -1.3333    1.2778

% Pearson's correlation coefficient

corrcoef (x)

ans =

    1.0000   -0.9948   -0.6150    0.9509
   -0.9948    1.0000    0.6622   -0.9229
   -0.6150    0.6622    1.0000   -0.4237
    0.9509   -0.9229   -0.4237    1.0000

spearman (x)

ans =

    1.0000   -0.2708   -0.1175   -0.2508
   -0.2708    1.0000    0.7583    0.6417
   -0.1175    0.7583    1.0000    0.7333
   -0.2508    0.6417    0.7333    1.0000

diary off