Provided by: infernal_1.1.5-2_amd64 
NAME
cmemit - sample sequences from a covariance model
SYNOPSIS
cmemit [options] <cmfile>
DESCRIPTION
The cmemit program samples (emits) sequences from the covariance model(s) in <cmfile>, and writes them to
output. Sampling sequences may be useful for a variety of purposes, including creating synthetic true
positives for benchmarks or tests.
The default is to sample ten unaligned sequence from each CM. Alternatively, with the -c option, you can
emit a single majority-rule consensus sequence; or with the -a option, you can emit an alignment.
The <cmfile> may contain a library of CMs, in which case each CM will be used in turn.
<cmfile> may be '-' (dash), which means reading this input from stdin rather than a file.
For models with zero basepairs, sequences are sampled from the profile HMM filter instead of the CM.
However, since these models will be nearly identical (unless special options were used in cmbuild to
prevent this), using the HMM instead of the CM will not change the output in a significant way, unless
the -l option is used. With -l, the HMM will be configured for equiprobable model begin and end
positions, while the CM will not. You can force cmemit to always sample from the CM with the --nohmmonly
option.
OPTIONS
-h Help; print a brief reminder of command line usage and available options.
-o <f> Save the synthetic sequences to file <f> rather than writing them to stdout.
-N <n> Generate <n> sequences. The default value for <n> is 10.
-u Write the generated sequences in unaligned format (FASTA). This is the default behavior.
-a Write the generated sequences in an aligned format (STOCKHOLM) with consensus structure annotation
rather than FASTA. Other output formats are possible with the --outformat option.
-c Predict a single majority-rule consensus sequence instead of sampling sequences from the CM´s
probability distribution. Highly conserved residues (base paired residues that score higher than
3.0 bits, or single stranded residues that score higher than 1.0 bits) are shown in upper case;
others are shown in lower case.
-e <n> Embed the CM emitted sequences in a larger randomly generated sequence of length <n> generated
from an HMM that was trained on real genomic sequences with various GC contents (the same HMM used
by cmcalibrate). You can use the --iid option to generate 25% A, C, G, and U sequence instead.
The CM emitted sequence will begin at a random position within the larger sequence and will be
included in its entirety unless the --u5p or --u3p options are used. When -e is used in
combination with --u5p, the CM emitted sequence will always begin at position 1 of the larger
sequence and will be truncated 5'. When used in combination --u3p the CM emitted sequence will
always end at position <n> of the larger sequence and will be truncated 3'.
-l Configure the CMs into local mode before emitting sequences. By default the model will be in
global mode. In local mode, large insertions and deletions are more common than in global mode.
OPTIONS FOR TRUNCATING EMITTED SEQUENCES
--u5p Truncate all emitted sequences at a randomly chosen start position <n>, by only outputting
residues beginning at <n>. A different start point is randomly chosen for each sequence.
--u3p Truncate all emitted sequences at a randomly chosen end position <n>, by only outputting residues
up to position <n>. A different end point is randomly chosen for each sequence.
--a5p <n>
In combination with the -a option, truncate the emitted alignment at a randomly chosen start match
position <n>, by only outputting alignment columns for positions after match state <n> - 1. <n>
must be an integer between 0 and the consensus length of the model (which can be determined using
the cmstat program. As a special case, using 0 as <n> will result in a randomly chosen start
position.
--a3p <n>
In combination with the -a option, truncate the emitted alignment at a randomly chosen end match
position <n>, by only outputting alignment columns for positions before match state <n> + 1. <n>
must be an integer between 1 and the consensus length of the model (which can be determined using
the cmstat program). As a special case, using 0 as <n> will result in a randomly chosen end
position.
OTHER OPTIONS
--seed <n>
Seed the random number generator with <n>, an integer >= 0. If <n> is nonzero, stochastic sampling
of sequences will be reproducible; the same command will give the same results. If <n> is 0, the
random number generator is seeded arbitrarily, and stochastic samplings will vary from run to run
of the same command. The default seed is 0.
--iid With -e, generate the larger sequences as 25% each A, C, G and U.
--rna Specify that the emitted sequences be output as RNA sequences. This is true by default.
--dna Specify that the emitted sequences be output as DNA sequences. By default, the output alphabet is
RNA.
--idx <n>
Specify that the emitted sequences be named starting with <modelname>.<n>. By default <n> is 1.
--outformat <s>
With -a, specify the output alignment format as <s>. Acceptable formats are: Pfam, AFA, A2M,
Clustal, and Phylip. AFA is aligned fasta. Only Pfam and Stockholm alignment formats will include
consensus structure annotation.
--tfile <f>
Dump tabular sequence parsetrees (tracebacks) for each emitted sequence to file <f>. Primarily
useful for debugging.
--exp <x>
Exponentiate the emission and transition probabilities of the CM by <x> and then renormalize those
distributions before emitting sequences. This option changes the CM probability distribution of
parsetrees relative to default. With <x> less than 1.0 the emitted sequences will tend to have
lower bit scores upon alignment to the CM. With <x> greater than 1.0, the emitted sequences will
tend to have higher bit scores upon alignment to the CM. This bit score difference will increase
as <x> moves further away from 1.0 in either direction. If <x> equals 1.0, this option has no
effect relative to default. This option is useful for generating sequences that are either more
difficult ( <x> < 1.0) or easier ( <x> > 1.0) for the CM to distinguish as homologous from
background, random sequence.
--hmmonly
Emit from the filter profile HMM instead of the CM.
--nohmmonly
Never emit from the filter profile HMM, always use the CM, even for models with zero basepairs.
SEE ALSO
See infernal(1) for a master man page with a list of all the individual man pages for programs in the
Infernal package.
For complete documentation, see the user guide that came with your Infernal distribution (Userguide.pdf);
or see the Infernal web page (http://eddylab.org/infernal/).
COPYRIGHT
Copyright (C) 2023 Howard Hughes Medical Institute.
Freely distributed under the BSD open source license.
For additional information on copyright and licensing, see the file called COPYRIGHT in your Infernal
source distribution, or see the Infernal web page (http://eddylab.org/infernal/).
AUTHOR
http://eddylab.org
Infernal 1.1.5 Sep 2023 cmemit(1)