Reading or writing a GFF-table from/to file.
Name of file with a GFF-table.
A table (
Name of file.
A GFF-table is simply a
tibble with columns
adhering to the format specified by the GFF3 format, see
https://github.com/The-Sequence-Ontology/Specifications/blob/master/gff3.md for details. There is
one row for each feature.
The following columns should always be in a full
gff.table of the GFF3 format:
Seqid. A unique identifier of the genomic sequence on which the feature resides.
Source. A description of the procedure that generated the feature, e.g.
Type The type of feature, e.g.
Start. The leftmost coordinate. This is the start if the feature is on the Sense strand, but the end if it is on the Antisense strand.
End. The rightmost coordinate. This is the end if the feature is on the Sense strand, but the start if it is on the Antisense strand.
Score. A numeric score (E-value, P-value) from the
"+" indicates Sense strand, a
Phase. Only relevant for coding genes. the values 0, 1 or 2 indicates the reading frame, i.e.
the number of bases to offset the
Start in order to be in the reading frame.
Attributes. A single string with semicolon-separated tokens prociding additional information.
Missing values are described by
"." in the GFF3 format. This is also done here, except for the
numerical columns Start, End, Score and Phase. Here
NA is used, but this is replaced by
"." when writing to file.
readGFF function will also read files where sequences in FASTA format are added after
the GFF-table. This file section must always start with the line
##FASTA. This fasta object
is added to the GFF-table as an attribute (use
attr(gff.tbl, "FASTA") to retrieve it).
readGFF returns a
gff.table with the columns described above.
writeGFF writes the supplied
gff.table to a text-file.
Lars Snipen and Kristian Hovde Liland.
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