[Numpy-discussion] syntax for obtaining rank of two columns?

JJ josh8912 at yahoo.com
Thu Jun 15 17:56:56 CDT 2006


Hello.  I am a matlab user learning the syntax of
numpy.  Id like to check that I am not missing some
easy steps on column selection and concatenation.  The
example task is to determine if two columns selected
out of an array are of full rank (rank 2).  Lets say
we have an array d that is size (10,10) and we select
the ith and jth columns to test their rank.  In matlab
the command is quite simple:

rank([d(:,i),d(:,j)])

In numpy, the best I have thought of so far is:

linalg.lstsq(transpose(vstack((d[:,i],d[:,j]))), \
ones((shape(transpose(vstack((d[:,i],d[:,j]))))  \
[0],1),'d'))[2]

Im thinking there must be a less awkward way.  Any
ideas?  

JJ

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