Class: Bio::Fetch
Overview
DESCRIPTION
The Bio::Fetch class provides an interface to dbfetch servers. Given a database name and an accession number, these servers return the associated record. For example, for the embl database on the EBI, that would be a nucleic or amino acid sequence.
Possible dbfetch servers include:
Note that old URL www.ebi.ac.uk/cgi-bin/dbfetch still alives probably because of compatibility, but using the new URL is recommended.
Historically, there were other dbfetch servers including:
-
bioruby.org/cgi-bin/biofetch.rb (default before BioRuby 1.4)
But they are unavailable now.
If you’re behind a proxy server, be sure to set your HTTP_PROXY environment variable accordingly.
USAGE
require 'bio'
# Retrieve the sequence of accession number M33388 from the EMBL
# database.
server = Bio::Fetch::EBI.new #uses EBI server
puts server.fetch('ena_sequence','M33388')
# database name "embl" can also be used though it is not officially listed
puts server.fetch('embl','M33388')
# Do the same thing with explicitly giving the URL.
server = Bio::Fetch.new(Bio::Fetch::EBI::URL) #uses EBI server
puts server.fetch('ena_sequence','M33388')
# Do the same thing without creating a Bio::Fetch::EBI object.
puts Bio::Fetch::EBI.query('ena_sequence','M33388')
# To know what databases are available on the dbfetch server:
server = Bio::Fetch::EBI.new
puts server.databases
# Some databases provide their data in different formats (e.g. 'fasta',
# 'genbank' or 'embl'). To check which formats are supported by a given
# database:
puts server.formats('embl')
Direct Known Subclasses
Defined Under Namespace
Classes: EBI
Instance Attribute Summary collapse
-
#database ⇒ Object
The default database to query – This will be used by the get_by_id method ++.
Instance Method Summary collapse
-
#databases ⇒ Object
Using this method, the user can ask a dbfetch server what databases it supports.
-
#fetch(db, id, style = 'raw', format = nil) ⇒ Object
Fetch a database entry as specified by database (db), entry id (id), ‘raw’ text or ‘html’ (style), and format.
-
#formats(database = @database) ⇒ Object
Lists the formats that are available for a given database.
-
#get_by_id(id) ⇒ Object
Get raw database entry by id.
-
#initialize(url = nil) ⇒ Fetch
constructor
Create a new Bio::Fetch server object that can subsequently be queried using the Bio::Fetch#fetch method.
-
#maxids ⇒ Object
A dbfetch server will only return entries up to a given maximum number.
Constructor Details
#initialize(url = nil) ⇒ Fetch
Create a new Bio::Fetch server object that can subsequently be queried using the Bio::Fetch#fetch method.
You must specify url of a server. The preset default server is deprecated.
If you want to use a server without explicitly specifying the URL, use Bio::Fetch::EBI.new that uses EBI Dbfetch server.
Arguments:
-
url: URL of dbfetch server. (no default value)
- Returns
-
Bio::Fetch object
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# File 'lib/bio/io/fetch.rb', line 140 def initialize(url = nil) unless url then raise ArgumentError, "No server URL is given in Bio::Fetch.new. The default server URL value have been deprecated. You must explicitly specify the url or use Bio::Fetch::EBI for using EBI Dbfetch." end @url = url end |
Instance Attribute Details
#database ⇒ Object
The default database to query – This will be used by the get_by_id method ++
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# File 'lib/bio/io/fetch.rb', line 151 def database @database end |
Instance Method Details
#databases ⇒ Object
Using this method, the user can ask a dbfetch server what databases it supports. This would normally be the first step you’d take when you use a dbfetch server for the first time. Example:
server = Bio::Fetch.new()
puts server.databases # returns "aa aax bl cpd dgenes dr ec eg emb ..."
This method works for EBI Dbfetch server (and for the bioruby dbfetch server). Not all servers support this method.
- Returns
-
array of database names
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# File 'lib/bio/io/fetch.rb', line 192 def databases _get_single('info', 'dbs').strip.split(/\s+/) end |
#fetch(db, id, style = 'raw', format = nil) ⇒ Object
Fetch a database entry as specified by database (db), entry id (id), ‘raw’ text or ‘html’ (style), and format.
Examples:
server = Bio::Fetch.new('http://www.ebi.ac.uk/cgi-bin/dbfetch')
puts server.fetch('embl','M33388','raw','fasta')
puts server.fetch('refseq','NM_12345','html','embl')
Arguments:
-
database: name of database to query (see Bio::Fetch#databases to get list of supported databases)
-
id: single ID or ID list separated by commas or white space
-
style: [raw|html] (default = ‘raw’)
-
format: name of output format (see Bio::Fetch#formats)
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# File 'lib/bio/io/fetch.rb', line 172 def fetch(db, id, style = 'raw', format = nil) query = [ [ 'db', db ], [ 'id', id ], [ 'style', style ] ] query.push([ 'format', format ]) if format _get(query) end |
#formats(database = @database) ⇒ Object
Lists the formats that are available for a given database. Like the Bio::Fetch#databases method, not all servers support this method. This method is available on the EBI Dbfetch server (and on the bioruby dbfetch server).
Example:
server = Bio::Fetch::EBI.new()
puts server.formats('embl') # returns [ "default", "annot", ... ]
Arguments:
- database
-
name of database you want the supported formats for
- Returns
-
array of formats
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# File 'lib/bio/io/fetch.rb', line 208 def formats(database = @database) if database query = [ [ 'info', 'formats' ], [ 'db', database ] ] _get(query).strip.split(/\s+/) end end |
#get_by_id(id) ⇒ Object
Get raw database entry by id. This method lets the Bio::Registry class use Bio::Fetch objects.
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# File 'lib/bio/io/fetch.rb', line 155 def get_by_id(id) fetch(@database, id) end |
#maxids ⇒ Object
A dbfetch server will only return entries up to a given maximum number. This method retrieves that number from the server. As for the databases and formats methods, not all servers support the maxids method. This method is available on the EBI Dbfetch server (and on the bioruby dbfetch server).
Example:
server = Bio::Fetch::EBI.new
puts server.maxids # currently returns 200
Arguments: none
- Returns
-
number
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# File 'lib/bio/io/fetch.rb', line 228 def maxids _get_single('info', 'maxids').to_i end |