Read GFF Files
This function reads a file in general feature format version 3 (GFF3) and returns a data frame.
read.gff(file, na.strings = c(".", "?"), GFF3 = TRUE)
file |
a file name specified by a character string. |
na.strings |
the strings in the GFF file that will be converted as NA's (missing values). |
GFF3 |
a logical value specifying whether if the file is formatted according to version 3 of GFF. |
The returned data frame has its (column) names correctly set (see References) and the categorical variables (seqid, source, type, strand, and phase) set as factors.
This function should be more efficient than using read.delim
.
GFF2 (aka GTF) files can also be read: use GFF3 = FALSE
to have
the correct field names. Note that GFF2 files and GFF3 files have the
same structure, although some fields are slightly different (see
reference).
The file can be gz-compressed (see examples), but not zipped.
NULL
Emmanuel Paradis
## Not run: ## requires to be connected on Internet d <- "https://ftp.ensembl.org/pub/release-86/gff3/homo_sapiens/" f <- "Homo_sapiens.GRCh38.86.chromosome.MT.gff3.gz" download.file(paste0(d, f), "mt_gff3.gz") ## If the above command doesn't work, you may copy/paste the full URL in ## a Web browser instead. gff.mito <- read.gff("mt_gff3.gz") ## the lengths of the sequence features: gff.mito$end - (gff.mito$start - 1) table(gff.mito$type) ## where the exons start: gff.mito$start[gff.mito$type == "exon"] ## End(Not run)
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