makeLinkedTxome reads the digest associated with a Salmon
index at indexDir, and links it to key information
about the transcriptome, including the source, organism,
release, and genome (these are custom character strings),
as well as the locations (e.g. local, HTTP, or FTP) for one or more fasta
files and one gtf file. loadLinkedTxome loads this
information from a JSON file. See Details.
makeLinkedTxome(
indexDir,
source,
organism,
release,
genome,
fasta,
gtf,
write = TRUE,
jsonFile
)
loadLinkedTxome(jsonFile)the local path to the Salmon index
the source of transcriptome (e.g. "de-novo"). Note: if you specify "GENCODE" or "Ensembl", this will trigger behavior by tximeta that may not be desired: e.g. attempts to download canonical transcriptome data from AnnotationHub (unless useHub=FALSE when running tximeta) and parsing of Ensembl GTF using ensembldb (which may fail if the GTF file has been modified). For transcriptomes that are defined by local GTF files, it is recommended to use the terms "LocalGENCODE" or "LocalEnsembl". Setting "LocalEnsembl" will also strip version numbers from the FASTA transcript IDs to enable matching with the Ensembl GTF.
organism (e.g. "Homo sapiens")
release number (e.g. "27")
genome (e.g. "GRCh38", or "none")
location(s) for the FASTA transcript sequences (of which the transcripts used to build the index is equal or a subset). This can be a local path, or an HTTP or FTP URL
location for the GTF/GFF file
(of which the transcripts used to build the index is equal or a subset).
This can be a local path, or an HTTP or FTP URL
While the fasta argument can take a vector of length greater than one
(more than one FASTA file containing transcripts used in indexing),
the gtf argument has to be a single GTF/GFF file.
This can also be a serialized GRanges object (location of a .rds file)
imported with rtracklayer.
If transcripts were added to a standard set of reference transcripts (e.g. fusion genes,
or pathogen transcripts), it is recommended that the tximeta user would manually
add these to the GTF/GFF file, and post the modified GTF/GFF publicly, such as
on Zenodo. This enables consistent annotation and downstream annotation
tasks, such as by summarizeToGene.
logical, should a JSON file be written out which documents the transcriptome digest and metadata? (default is TRUE)
the path to the json file for the linkedTxome
nothing, the function is run for its side effects
makeLinkedTxome links the information about the transcriptome
used for quantification in two ways:
1) the function will store a record in tximeta's cache such that
future import of quantification data will automatically access and
parse the GTF as if the transcriptome were one of those automatically
detected by tximeta. Then all features of tximeta (e.g. summarization
to gene, programmatic adding of IDs or metadata) will be available;
2) it will by default write out a JSON file
that can be shared, or posted online, and which can be read by
loadLinkedTxome which will store the information in tximeta's
cache. This should make the full quantification-import pipeline
computationally reproducible / auditable even for transcriptomes
which differ from those provided by references (GENCODE, Ensembl,
RefSeq).
For further details please see the "Linked transcriptomes" section of the tximeta vignette.
# point to a Salmon quantification file with an additional artificial transcript
dir <- system.file("extdata/salmon_dm", package="tximportData")
file <- file.path(dir, "SRR1197474.plus", "quant.sf")
coldata <- data.frame(files=file, names="SRR1197474", sample="1",
stringsAsFactors=FALSE)
# now point to the Salmon index itself to create a linkedTxome
# as the index will not match a known txome
indexDir <- file.path(dir, "Dm.BDGP6.22.98.plus_salmon-0.14.1")
# point to the source FASTA and GTF:
fastaFTP <- c("ftp://ftp.ensembl.org/pub/release-98/fasta/drosophila_melanogaster/cdna/Drosophila_melanogaster.BDGP6.22.cdna.all.fa.gz",
"ftp://ftp.ensembl.org/pub/release-98/fasta/drosophila_melanogaster/ncrna/Drosophila_melanogaster.BDGP6.22.ncrna.fa.gz",
"extra_transcript.fa.gz")
gtfPath <- file.path(dir, "Drosophila_melanogaster.BDGP6.22.98.plus.gtf.gz")
# now create a linkedTxome, linking the Salmon index to its FASTA and GTF sources
makeLinkedTxome(indexDir=indexDir, source="Ensembl", organism="Drosophila melanogaster",
release="98", genome="BDGP6.22", fasta=fastaFTP, gtf=gtfPath, write=FALSE)
#> NOTE: linkedTxome with source='Ensembl', ensembldb will be used to parse GTF.
#> this may produce errors if the GTF is not from Ensembl, or has been modified.
#> set useHub=FALSE in tximeta to avoid download of reference txome from AnnotationHub.
#> alternatively use a different string for source argument
#> saving linkedTxome in bfc
# to clear the entire linkedTxome table
# (don't run unless you want to clear this table!)
# bfcloc <- getTximetaBFC()
# bfc <- BiocFileCache(bfcloc)
# bfcremove(bfc, bfcquery(bfc, "linkedTxomeTbl")$rid)