id2name {GenomicFeatures} | R Documentation

## Map internal ids to external names for a given feature type

### Description

Utility function for retrieving the mapping from the internal ids to the external names of a given feature type.

### Usage

    id2name(txdb, feature.type=c("tx", "exon", "cds"))

### Arguments

`txdb` | A TxDb object.
`feature.type` | The feature type for which the mapping must be retrieved.

### Details

Transcripts, exons and CDS in a TxDb object are stored in seperate tables where the primary key is an integer called feature internal id. This id is stored in the `"tx_id"` column for transcripts, in the `"exon_id"` column for exons, and in the `"cds_id"` column for CDS. Unlike other commonly used ids like Entrez Gene IDs or Ensembl IDs, this internal id was generated at the time the TxDb object was created and has no meaning outside the scope of this object.

The `id2name` function can be used to translate this internal id into a more informative id or name called feature external name. This name is stored in the `"tx_name"` column for transcripts, in the `"exon_name"` column for exons, and in the `"cds_name"` column for CDS.

Note that, unlike the feature internal id, the feature external name is not guaranteed to be unique or even defined (the column can contain `NA`s).

### Value

A named character vector where the names are the internal ids and the values the external names.

### Author(s)

Hervé Pagès

### See Also

- `transcripts`, `transcriptsBy`, and `transcriptsByOverlaps`, for how to extract genomic features from a TxDb object.

- The TxDb class.

### Examples

    txdb1_file <- system.file("extdata", "hg19_knownGene_sample.sqlite",
                              package="GenomicFeatures")
    txdb1 <- loadDb(txdb1_file)
    id2name(txdb1, feature.type="tx")[1:4]
    id2name(txdb1, feature.type="exon")[1:4]
    id2name(txdb1, feature.type="cds")[1:4]

    txdb2_file <- system.file("extdata", "Biomart_Ensembl_sample.sqlite",
                              package="GenomicFeatures")
    txdb2 <- loadDb(txdb2_file)
    id2name(txdb2, feature.type="tx")[1:4]
    id2name(txdb2, feature.type="exon")[1:4]
    id2name(txdb2, feature.type="cds")[1:4]

[Package GenomicFeatures version 1.40.1 Index]