[Biopython] ClastalW and creating own log odd table

[George Devaniranjan]

I want to try set up a log-odds matrix for my own and was experimenting with
the BIOPYTHON TUTURIOL


import os
from Bio import Clustalw
from Bio.Clustalw import MultipleAlignCL
cline=MultipleAlignCL(os.path.join(os.curdir, 'sequence.fasta')
cline.set_output('test.aln')

alignment =Clustalw.do_alignment(cline)


The output was as follows..........

sh: clustalw: command not found
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
  File "/usr/local/lib/python2.4/site-packages/Bio/Clustalw/__init__.py",
line 134, in do_alignment
    raise IOError("Output .aln file %s not produced, commandline: %s"
IOError: Output .aln file test.aln not produced, commandline: clustalw
./sequence.fasta -OUTFILE=test.aln


I am not sure where I am going wrong.
Thank you,
George