CODEWITHSUNDEEP
matrixvectordatasetoctavescatter-plot
user3377126
user3377126

Reputation: 2171

Cannot use scatterplot in Octave

I was learning how to do machine learning on mldata.org and I was watching a video on Youtube on how to use the data (https://www.youtube.com/watch?v=zY0UhXPy8fM) (2:50). Using the same data, I tried to follow exactly what he did and create a scatterplot of the dataset. However when he used the scatterplot command, it worked perfectly on his side, but I cannot do it on myside.

Can anyone explain what's wrong and what I should do?

octave:2> load banana_data.octave
octave:3> pkg load communications
octave:4> whos
Variables in the current scope:

   Attr Name        Size                     Bytes  Class
   ==== ====        ====                     =====  ===== 
        data        2x5300                   84800  double
        label       1x5300                   42400  double

Total is 15900 elements using 127200 bytes
octave:5> scatterplot(data, label)
error: scatterplot: real X must be a vector or a 2-column matrix
error: called from:
error:   /home/anthony/octave/communications-1.2.0/scatterplot.m at line 69, column 7

Upvotes: 0

Views: 790

Answers (1)

ederag
ederag

Reputation: 2509

The error message says it all. Your data is a 2-row matrix, and not a 2-column matrix as it should be. Just transpose it with .'.

scatterplot(data.')

I dropped the label argument since it is not compatible with the communications toolbox, either in matlab or in octave.

Update:

According to news('communications'),

The plotting functions eyediagram' andscatterplot' have improved Matlab compatibility

This may be why the behaviour is different. Be ready to find other glitches, as the octave 3.2.4 used in this course is about 5 years old.

In order to use the label, you should rather use the standard octave scatter function. Colors could be changed by choosing another colormap.

colormap(cool(256))
scatter(data(1,:), data(2,:), 6, label, "filled")

with scatter

Upvotes: 1

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