read.snp | R Documentation |
The function read.snp
reads a SNP data file with extension '.snp' and
converts it into a genlight object. This format is devoted to
handle biallelic SNP only, but can accommodate massive datasets such as
complete genomes with considerably less memory than other formats.
read.snp( file, quiet = FALSE, chunkSize = 1000, parallel = FALSE, n.cores = NULL, ... )
file |
a character string giving the path to the file to convert, with the extension ".snp". |
quiet |
logical stating whether a conversion messages should be printed (TRUE,default) or not (FALSE). |
chunkSize |
an integer indicating the number of genomes to be read at a time; larger values require more RAM but decrease the time needed to read the data. |
parallel |
a logical indicating whether multiple cores -if available-
should be used for the computations (TRUE, default), or not (FALSE);
requires the package |
n.cores |
if |
... |
other arguments to be passed to other functions - currently not used. |
The function reads data by chunks of a few genomes (minimum 1, no maximum)
at a time, which allows one to read massive datasets with negligible RAM
requirements (albeit at a cost of computational time). The argument
chunkSize
indicates the number of genomes read at a time. Increasing
this value decreases the computational time required to read data in, while
increasing memory requirements.
A description of the .snp format is provided in an example file distributed with adegenet (see example below).
=== The .snp format ===
Details of the .snp format can be found in the example file distributed with
adegenet (see below), or on the adegenet website (type adegenetWeb()
in R).
an object of the class "genlight"
Thibaut Jombart t.jombart@imperial.ac.uk
- ?genlight
for a description of the class
"genlight"
.
- read.PLINK
: read SNPs in PLINK's '.raw' format.
- fasta2genlight
: extract SNPs from alignments with fasta
format.
- df2genind
: convert any multiallelic markers into adegenet
"genlight"
.
- import2genind
: read multiallelic markers from various
software into adegenet.
## Not run: ## show the example file ## ## this is the path to the file: system.file("files/exampleSnpDat.snp",package="adegenet") ## show its content: file.show(system.file("files/exampleSnpDat.snp",package="adegenet")) ## read the file obj <- read.snp(system.file("files/exampleSnpDat.snp",package="adegenet"), chunk=2) obj as.matrix(obj) ploidy(obj) alleles(obj) locNames(obj) ## End(Not run)
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