The master copies of EMBOSS documentation are available at on the EMBOSS Wiki.

Please help by correcting and extending the Wiki pages.


Generate residue/base frequency table or plot


freak reads one or more sequences and a set of bases or residues to search for. It then calculates the frequency of these bases/residues in a window as it moves along the sequence. The frequency is output to a data file or (optionally) plotted.


The frequency of bases/residues is calculated in a window that is moved along the sequence. The window size and stepping value (number of positions the window is moved along each time) may be specified.


Here is a sample session with freak

% freak tembl:x65923 
Generate residue/base frequency table or plot
Residue letters [gc]: 
Output file [x65923.freak]: 

Go to the input files for this example
Go to the output files for this example

Command line arguments

   Standard (Mandatory) qualifiers (* if not always prompted):
  [-seqall]            seqall     Sequence(s) filename and optional format, or
                                  reference (input USA)
   -letters            string     [gc] Residue letters (Any string is
*  -graph              xygraph    [$EMBOSS_GRAPHICS value, or x11] Graph type
                                  (ps, hpgl, hp7470, hp7580, meta, cps, x11,
                                  tekt, tek, none, data, das, xterm, png, gif)
*  -outfile            outfile    [*.freak] Output file name

   Additional (Optional) qualifiers:
   -step               integer    [1] Stepping value (Any integer value)
   -window             integer    [30] Averaging window (Any integer value)

   Advanced (Unprompted) qualifiers:
   -plot               toggle     [N] Produce graphic

   Associated qualifiers:

   "-seqall" associated qualifiers
   -sbegin1            integer    Start of each sequence to be used
   -send1              integer    End of each sequence to be used
   -sreverse1          boolean    Reverse (if DNA)
   -sask1              boolean    Ask for begin/end/reverse
   -snucleotide1       boolean    Sequence is nucleotide
   -sprotein1          boolean    Sequence is protein
   -slower1            boolean    Make lower case
   -supper1            boolean    Make upper case
   -sformat1           string     Input sequence format
   -sdbname1           string     Database name
   -sid1               string     Entryname
   -ufo1               string     UFO features
   -fformat1           string     Features format
   -fopenfile1         string     Features file name

   "-graph" associated qualifiers
   -gprompt            boolean    Graph prompting
   -gdesc              string     Graph description
   -gtitle             string     Graph title
   -gsubtitle          string     Graph subtitle
   -gxtitle            string     Graph x axis title
   -gytitle            string     Graph y axis title
   -goutfile           string     Output file for non interactive displays
   -gdirectory         string     Output directory

   "-outfile" associated qualifiers
   -odirectory         string     Output directory

   General qualifiers:
   -auto               boolean    Turn off prompts
   -stdout             boolean    Write first file to standard output
   -filter             boolean    Read first file from standard input, write
                                  first file to standard output
   -options            boolean    Prompt for standard and additional values
   -debug              boolean    Write debug output to program.dbg
   -verbose            boolean    Report some/full command line options
   -help               boolean    Report command line options. More
                                  information on associated and general
                                  qualifiers can be found with -help -verbose
   -warning            boolean    Report warnings
   -error              boolean    Report errors
   -fatal              boolean    Report fatal errors
   -die                boolean    Report dying program messages

Standard (Mandatory) qualifiers Allowed values Default
(Parameter 1)
Sequence(s) filename and optional format, or reference (input USA) Readable sequence(s) Required
-letters Residue letters Any string is accepted gc
-graph Graph type EMBOSS has a list of known devices, including ps, hpgl, hp7470, hp7580, meta, cps, x11, tekt, tek, none, data, das, xterm, png, gif EMBOSS_GRAPHICS value, or x11
-outfile Output file name Output file <*>.freak
Additional (Optional) qualifiers Allowed values Default
-step Stepping value Any integer value 1
-window Averaging window Any integer value 30
Advanced (Unprompted) qualifiers Allowed values Default
-plot Produce graphic Toggle value Yes/No No

Input file format

freak reads normal sequence USAs.

Input files for usage example

'tembl:x65923' is a sequence entry in the example nucleic acid database 'tembl'

Database entry: tembl:x65923

ID   X65923; SV 1; linear; mRNA; STD; HUM; 518 BP.
AC   X65923;
DT   13-MAY-1992 (Rel. 31, Created)
DT   18-APR-2005 (Rel. 83, Last updated, Version 11)
DE   H.sapiens fau mRNA
KW   fau gene.
OS   Homo sapiens (human)
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae;
OC   Homo.
RN   [1]
RP   1-518
RA   Michiels L.M.R.;
RT   ;
RL   Submitted (29-APR-1992) to the EMBL/GenBank/DDBJ databases.
RL   L.M.R. Michiels, University of Antwerp, Dept of Biochemistry,
RL   Universiteisplein 1, 2610 Wilrijk, BELGIUM
RN   [2]
RP   1-518
RX   PUBMED; 8395683.
RA   Michiels L., Van der Rauwelaert E., Van Hasselt F., Kas K., Merregaert J.;
RT   "fau cDNA encodes a ubiquitin-like-S30 fusion protein and is expressed as
RT   an antisense sequence in the Finkel-Biskis-Reilly murine sarcoma virus";
RL   Oncogene 8(9):2537-2546(1993).
DR   H-InvDB; HIT000322806.
FH   Key             Location/Qualifiers
FT   source          1..518
FT                   /organism="Homo sapiens"
FT                   /chromosome="11q"
FT                   /map="13"
FT                   /mol_type="mRNA"
FT                   /clone_lib="cDNA"
FT                   /clone="pUIA 631"
FT                   /tissue_type="placenta"
FT                   /db_xref="taxon:9606"
FT   misc_feature    57..278
FT                   /note="ubiquitin like part"
FT   CDS             57..458
FT                   /gene="fau"
FT                   /db_xref="GDB:135476"
FT                   /db_xref="GOA:P62861"
FT                   /db_xref="HGNC:3597"
FT                   /db_xref="HSSP:1GJZ"
FT                   /db_xref="InterPro:IPR006846"
FT                   /db_xref="UniProtKB/Swiss-Prot:P35544"
FT                   /protein_id="CAA46716.1"
FT   misc_feature    98..102
FT                   /note="nucleolar localization signal"
FT   misc_feature    279..458
FT                   /note="S30 part"
FT   polyA_signal    484..489
FT   polyA_site      509
SQ   Sequence 518 BP; 125 A; 139 C; 148 G; 106 T; 0 other;
     ttcctctttc tcgactccat cttcgcggta gctgggaccg ccgttcagtc gccaatatgc        60
     agctctttgt ccgcgcccag gagctacaca ccttcgaggt gaccggccag gaaacggtcg       120
     cccagatcaa ggctcatgta gcctcactgg agggcattgc cccggaagat caagtcgtgc       180
     tcctggcagg cgcgcccctg gaggatgagg ccactctggg ccagtgcggg gtggaggccc       240
     tgactaccct ggaagtagca ggccgcatgc ttggaggtaa agttcatggt tccctggccc       300
     gtgctggaaa agtgagaggt cagactccta aggtggccaa acaggagaag aagaagaaga       360
     agacaggtcg ggctaagcgg cggatgcagt acaaccggcg ctttgtcaac gttgtgccca       420
     cctttggcaa gaagaagggc cccaatgcca actcttaagt cttttgtaat tctggctttc       480
     tctaataaaa aagccactta gttcagtcaa aaaaaaaa                               518

Output file format

Output files for usage example

File: x65923.freak

FREAK of X65923 from 1 to 518 Window 30 Step 1

1          0.500000
2          0.533333
3          0.566667
4          0.533333
5          0.533333
6          0.566667
7          0.566667
8          0.566667
9          0.600000
10         0.633333
11         0.633333
12         0.666667
13         0.666667
14         0.666667
15         0.666667
16         0.633333
17         0.666667
18         0.633333
19         0.633333
20         0.633333
21         0.666667
22         0.666667
23         0.700000
24         0.733333
25         0.700000
26         0.666667
27         0.633333
28         0.600000
29         0.566667
30         0.600000
31         0.633333
32         0.600000
33         0.600000
34         0.633333
35         0.600000
36         0.600000
37         0.566667
38         0.566667
39         0.533333
40         0.533333
41         0.500000
42         0.500000
43         0.500000
44         0.500000
45         0.533333
46         0.566667
47         0.566667
48         0.600000

  [Part of this file has been deleted for brevity]

439        0.433333
440        0.400000
441        0.366667
442        0.333333
443        0.333333
444        0.300000
445        0.333333
446        0.366667
447        0.400000
448        0.366667
449        0.333333
450        0.300000
451        0.333333
452        0.333333
453        0.333333
454        0.333333
455        0.300000
456        0.300000
457        0.300000
458        0.300000
459        0.300000
460        0.266667
461        0.266667
462        0.233333
463        0.233333
464        0.266667
465        0.300000
466        0.333333
467        0.300000
468        0.333333
469        0.333333
470        0.333333
471        0.333333
472        0.366667
473        0.333333
474        0.333333
475        0.333333
476        0.300000
477        0.300000
478        0.300000
479        0.333333
480        0.333333
481        0.300000
482        0.300000
483        0.266667
484        0.266667
485        0.266667
486        0.266667
487        0.266667
488        0.266667
489        0.266667

The ouput consists of a title line and then two columns containing the position of the start of the window and then the frequency in that window of the bases or residues being searched for.

Data files



The default set of bases is cg which will calculate the frequency of G + C bases within the default moving window of 30 bases.





Diagnostic Error Messages


Exit status

It always exits with status 0.

Known bugs


See also

Program name Description
backtranambig Back-translate a protein sequence to ambiguous nucleotide sequence
backtranseq Back-translate a protein sequence to a nucleotide sequence
banana Plot bending and curvature data for B-DNA
btwisted Calculate the twisting in a B-DNA sequence
chaos Draw a chaos game representation plot for a nucleotide sequence
charge Draw a protein charge plot
checktrans Reports STOP codons and ORF statistics of a protein
compseq Calculate the composition of unique words in sequences
dan Calculates nucleic acid melting temperature
density Draw a nucleic acid density plot
emowse Search protein sequences by digest fragment molecular weight
iep Calculate the isoelectric point of proteins
isochore Plots isochores in DNA sequences
mwcontam Find weights common to multiple molecular weights files
mwfilter Filter noisy data from molecular weights file
octanol Draw a White-Wimley protein hydropathy plot
pepinfo Plot amino acid properties of a protein sequence in parallel
pepstats Calculates statistics of protein properties
pepwindow Draw a hydropathy plot for a protein sequence
pepwindowall Draw Kyte-Doolittle hydropathy plot for a protein alignment
sirna Finds siRNA duplexes in mRNA
wordcount Count and extract unique words in DNA sequence(s)


Alan Bleasby (ajb ©
European Bioinformatics Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge CB10 1SD, UK


Written (Aug 2000) Alan Bleasby

Target users

This program is intended to be used by everyone and everything, from naive users to embedded scripts.