shuffle - randomize the sequences in a sequence file
reads a sequence file
randomizes each sequence, and prints the randomized sequences
in FASTA format on standard output. The sequence names
are unchanged; this allows you to track down the source
of each randomized sequence if necessary.
The default is to simply shuffle each input sequence, preserving
monosymbol composition exactly. To shuffle
each sequence while preserving both its monosymbol and disymbol
composition exactly, use the
options allow you to generate sequences with the same
Markov properties as each input sequence. With
for each input sequence, 0th order Markov statistics
are collected (e.g. symbol composition), and a new
sequence is generated with the same composition.
the generated sequence has the same 1st order
Markov properties as the input sequence (e.g.
the same disymbol frequencies).
Note that the default and
are similar; the shuffling algorithms preserve
composition exactly, while the Markov algorithms
only expect to generate a sequence of similar
composition on average.
Other shuffling algorithms are also available,
as documented below in the options.
Calculate 0th order Markov frequencies of each input sequence
(e.g. residue composition); generate output sequence
using the same 0th order Markov frequencies.
Calculate 1st order Markov frequencies for each input
sequence (e.g. diresidue composition); generate output
sequence using the same 1st order Markov frequencies.
The first residue of the output sequence is always
the same as the first residue of the input sequence.
Shuffle the input sequence while preserving both
monosymbol and disymbol composition exactly. Uses
an algorithm published by S.F. Altschul and B.W. Erickson,
Mol. Biol. Evol. 2:526-538, 1985.
Print brief help; includes version number and summary of
all options, including expert options.
Look only at the length of each input sequence; generate
an i.i.d. output protein sequence of that length,
using monoresidue frequencies typical of proteins
(taken from Swissprot 35).
different randomizations of each input sequence in
rather than the default of one.
Generate the output sequence by reversing the
input sequence. (Therefore only one "randomization"
per input sequence is possible, so it's
not worth using
if you use reversal.)
Truncate each input sequence to a fixed length of exactly
residues. If the input sequence is shorter than
it is discarded (therefore the output file may contain
fewer sequences than the input file).
If the input sequence is longer than
a contiguous subsequence is randomly chosen.
Regionally shuffle each input sequence in window sizes of
preserving local residue composition in each window.
Probably a better shuffling algorithm for biosequences
with nonstationary residue composition (e.g. composition
that is varying along the sequence, such as between
different isochores in human genome sequence).
(Babelfish). Autodetect and read a sequence file format other than the
default (FASTA). Almost any common sequence file format is recognized
(including Genbank, EMBL, SWISS-PROT, PIR, and GCG unaligned sequence
formats, and Stockholm, GCG MSF, and Clustal alignment formats). See
the printed documentation for a complete list of supported formats.
Specify that the sequence file is in format
rather than the default FASTA format.
Common examples include Genbank, EMBL, GCG,
PIR, Stockholm, Clustal, MSF, or PHYLIP;
see the printed documentation for a complete list
of accepted format names.
This option overrides the default expected format (FASTA)
Babelfish autodetection option.
Do not output any sequence description in the output file,
only the sequence names.
Set the random number seed to
If you want reproducible results, use the same seed each time.
uses a different seed each time, so does not generate
the same output in subsequent runs with the same input.
Biosquid and its documentation are Copyright (C) 1992-2003 HHMI/Washington University School of Medicine
Freely distributed under the GNU General Public License (GPL)
See COPYING in the source code distribution for more details, or contact me.
HHMI/Department of Genetics
Washington University School of Medicine
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St Louis, MO 63108 USA
FAX : 1-314-362-2157