getChromInfoFromEnsembl {GenomeInfoDb} | R Documentation

## Get chromosome information for an Ensembl species

### Description

`getChromInfoFromEnsembl` returns chromosome information like sequence names, lengths and circularity flags for a given Ensembl species e.g. Human, Cow, Saccharomyces cerevisiae, etc...

### Usage

    getChromInfoFromEnsembl(species,
                            release=NA, division=NA, use.grch37=FALSE,
                            assembled.molecules.only=FALSE,
                            include.non_ref.sequences=FALSE,
                            include.contigs=FALSE,
                            include.clones=FALSE,
                            map.NCBI=FALSE,
                            recache=FALSE,
                            as.Seqinfo=FALSE)

### Arguments

`species` | A single string specifying the name of an Ensembl species e.g. `"human"`, `"hsapiens"`, or `"Homo sapiens"`. Case is ignored. Alternatively the name of an assembly (e.g. `"GRCh38"`) or a taxonomy id (e.g. 9606) can be supplied.
`release` | The Ensembl release to query e.g. 89. If set to `NA` (the default), the current release is used.
`division` | `NA` (the default) or one of the EnsemblGenomes marts i.e. `"bacteria"`, `"fungi"`, `"metazoa"`, `"plants"`, or `"protists"`.
`use.grch37` | NOT TESTED YET! `TRUE` or `FALSE` (the default).
`assembled.molecules.only` | NOT IMPLEMENTED YET!
`include.non_ref.sequences` | TODO: DOCUMENT THIS!
`include.contigs` | Whether or not sequences for which `coord_system` is set to `"contig"` should be included. They are not included by default. Note that the dataset for Human contains more than one hundred thousands contigs!
`include.clones` | Whether or not sequences for which `coord_system` is set to `"clone"` should be included. They are not included by default. Note that the dataset for Human contains more than one hundred thousands clones!
`map.NCBI` | `TRUE` or `FALSE` (the default). If `TRUE` then NCBI chromosome information is bound to the result. This information is retrieved from NCBI by calling `getChromInfoFromNCBI` on the NCBI assembly that the Ensembl species is based on. Then the data frame returned by `getChromInfoFromNCBI` ("NCBI chrom info") is mapped and bound to the data frame returned by `getChromInfoFromEnsembl` ("Ensembl chrom info"). This "map and bind" operation is similar to a `JOIN` in SQL. Note that not all rows in the "Ensembl chrom info" data frame are necessarily mapped to a row in the "NCBI chrom info" data frame. For the unmapped rows the NCBI columns in the final data frame are filled with NAs (`LEFT JOIN` in SQL). The primary use case for using `map.NCBI=TRUE` is to map Ensembl sequence names to NCBI sequence names.
`recache` | `getChromInfoFromEnsembl` uses a cache mechanism so the chromosome information of a given dataset only gets downloaded once during the current R session (note that the caching is done in memory so cached information does NOT persist across sessions). Setting `recache` to `TRUE` forces a new download (and recaching) of the chromosome information for the specified dataset.
`as.Seqinfo` | `TRUE` or `FALSE` (the default). If `TRUE` then a Seqinfo object is returned instead of a data frame. Note that only the `name`, `length`, and `circular` columns of the data frame are used to make the Seqinfo object. All the other columns are ignored (and lost).

### Details

COMING SOON...

### Value

For `getChromInfoFromEnsembl`: By default, a 7-column data frame with columns:

1. `name`: character.

2. `length`: integer.

3. `coord_system`: factor.

4. `synonyms`: list.

5. `toplevel`: logical.

6. `non_ref`: logical.

7. `circular`: logical.

and with attribute `species_info` which contains details about the species that was used to obtaine the data.

If `map.NCBI` is `TRUE`, then 7 "NCBI columns" are added to the result:

- `NCBI.SequenceName`: character.

- `NCBI.SequenceRole`: factor.

- `NCBI.AssignedMolecule`: factor.

- `NCBI.GenBankAccn`: character.

- `NCBI.Relationship`: factor.

- `NCBI.RefSeqAccn`: character.

- `NCBI.AssemblyUnit`: factor.

Note that the names of the "NCBI columns" are those returned by `getChromInfoFromNCBI` but with the `NCBI.` prefix added to them.

### Author(s)

H. Pagès

### See Also

- `getChromInfoFromNCBI` and `getChromInfoFromUCSC` for getting chromosome information for an NCBI assembly or UCSC genome.

- Seqinfo objects.

### Examples

    ## ---------------------------------------------------------------------
    ## A. BASIC EXAMPLES
    ## ---------------------------------------------------------------------

    ## Internet access required!

    ## === Worm ===
    ## https://uswest.ensembl.org/Caenorhabditis_elegans

    celegans <- getChromInfoFromEnsembl("celegans")
    attr(celegans, "species_info")

    getChromInfoFromEnsembl("celegans", as.Seqinfo=TRUE)

    celegans <- getChromInfoFromEnsembl("celegans", map.NCBI=TRUE)

    ## === Yeast ===
    ## https://uswest.ensembl.org/Saccharomyces_cerevisiae

    scerevisiae <- getChromInfoFromEnsembl("scerevisiae")
    attr(scerevisiae, "species_info")

    getChromInfoFromEnsembl("scerevisiae", as.Seqinfo=TRUE)

    scerevisiae <- getChromInfoFromEnsembl("scerevisiae", map.NCBI=TRUE)

    ## Arabidopsis thaliana:
    athaliana <- getChromInfoFromEnsembl("athaliana", division="plants",
                                         map.NCBI=TRUE)
    attr(athaliana, "species_info")

    ## ---------------------------------------------------------------------
    ## Temporary stuff that needs to go away...
    ## ---------------------------------------------------------------------

    ## TODO: Check all species for which an NCBI assembly is registered!
    ## Checked so far (with current Ensembl release i.e. 99):
    ## - celegans       OK
    ## - scerevisiae    OK
    ## - athaliana      OK
    ## - btaurus        OK
    ## - sscrofa        OK

    ## Not run:
    ## WORK IN PROGRESS!!!
    library(GenomeInfoDb)

    .do_join <- GenomeInfoDb:::.do_join
    .map_Ensembl_seqlevels_to_NCBI_seqlevels <-
        GenomeInfoDb:::.map_Ensembl_seqlevels_to_NCBI_seqlevels

    .map_Ensembl_seqlevels_to_NCBI_seqlevels(
        paste0("ENS_", 1:26),
        CharacterList(c(list(c(aa="INSDC1", bb="GNBK7"), c("INSDC2", "RefSeq3")),
                        rep(list(NULL), 23), list("NCBI_7"))),
        paste0("NCBI_", 1:10),
        paste0("GNBK", c(1:8, NA, 9)),
        c(paste0("REFSEQ", c(1:7, 1, 1)), NA),
        verbose=TRUE
    )

    map_to_NCBI <- function(Ensembl_chrom_info, NCBI_chrom_info,
                            special_mappings=NULL)
    {
        .map_Ensembl_seqlevels_to_NCBI_seqlevels(
             Ensembl_chrom_info[ , "name"],
             Ensembl_chrom_info[ , "synonyms"],
             NCBI_chrom_info[ , "SequenceName"],
             NCBI_chrom_info[ , "GenBankAccn"],
             NCBI_chrom_info[ , "RefSeqAccn"],
             special_mappings=special_mappings,
             verbose=TRUE)
    }

    ## ------------------------------------------------------------------------
    ## Human
    ## https://uswest.ensembl.org/Homo_sapiens/
    ## Based on GRCh38.p13 (GCA_000001405.28)

    ## Return 944 rows
    human_chrom_info <- getChromInfoFromEnsembl("hsapiens")
    #                 1 id: 131550  <- ref chromosome
    # CHR_HSCHR1_1_CTG3 id: 131561  <- non-ref chromosome
    #     HSCHR1_1_CTG3 id: 131562  <- scaffold (no scaffold is non_ref)

    ## Map to NCBI
    ## Summary:
    ## - 639/640 NCBI sequences are reverse-mapped.
    ## - Restricted mapping is one-to-one.
    GRCh38.p13 <- getChromInfoFromNCBI("GRCh38.p13")
    L2R <- map_to_NCBI(human_chrom_info, GRCh38.p13)
    ## The only sequence in GRCh38.p13 that cannot be mapped to Ensembl is
    ## HG2139_PATCH (was introduced in GRCh38.p2)! Why? What's special about
    ## this patch?
    GRCh38.p13$mapped <- tabulate(L2R, nbins=nrow(GRCh38.p13)) != 0L
    table(GRCh38.p13$SequenceRole, GRCh38.p13$mapped)
    #                        FALSE TRUE
    #   assembled-molecule       0   25
    #   alt-scaffold             0  261
    #   unlocalized-scaffold     0   42
    #   unplaced-scaffold        0  127
    #   pseudo-scaffold          0    0
    #   fix-patch                1  112
    #   novel-patch              0   72
    human_chrom_info <- .do_join(human_chrom_info, GRCh38.p13, L2R)
    table(human_chrom_info$SequenceRole, human_chrom_info$toplevel)
    #                       FALSE TRUE
    #  assembled-molecule       0   25
    #  alt-scaffold           261    0
    #  unlocalized-scaffold     0   42
    #  unplaced-scaffold        0  127
    #  pseudo-scaffold          0    0
    #  fix-patch              112    0
    #  novel-patch             72    0

    #hsa_seqlevels <- readRDS("hsapiens_gene_ensembl_txdb_seqlevels.rds")

    ## ------------------------------------------------------------------------
    ## Mouse
    ## https://uswest.ensembl.org/Mus_musculus/
    ## Based on GRCm38.p6 (GCA_000001635.8)

    ## Return 258 rows
    mouse_chrom_info <- getChromInfoFromEnsembl("mmusculus")

    ## Map to NCBI
    ## Summary:
    ## - 139/239 NCBI sequences are reverse-mapped.
    ## - Restricted mapping is NOT one-to-one: 2 Ensembl sequences (NC_005089.1
    ##   and MT) are both mapped to NCBI MT.
    GRCm38.p6 <- getChromInfoFromNCBI("GRCm38.p6")
    L2R <- map_to_NCBI(mouse_chrom_info, GRCm38.p6)
    ## 100 sequences in GRCm38.p6 are not mapped:
    GRCm38.p6$mapped <- tabulate(L2R, nbins=nrow(GRCm38.p6)) != 0L
    table(GRCm38.p6$SequenceRole, GRCm38.p6$mapped)
    #                        FALSE TRUE
    #   assembled-molecule       0   22
    #   alt-scaffold            99    0
    #   unlocalized-scaffold     0   22
    #   unplaced-scaffold        0   22
    #   pseudo-scaffold          0    0
    #   fix-patch                1   64
    #   novel-patch              0    9
    ## OK so Ensembl doesn't include the alt-scaffolds for Mouse. BUT WHAT
    ## HAPPENED TO THIS ONE fix-patch SEQUENCE (MG4237_PATCH) THAT IS NOT
    ## MAPPED? Found it in seq_region_synonym table! It's seq_region_id=100405.
    ## Hey but that seq_region_id is **NOT** in the seq_region table!!! THIS
    ## VIOLATES FOREIGN KEY CONSTRAINT!!!!
    mouse_chrom_info <- .do_join(mouse_chrom_info, GRCm38.p6, L2R)
    ## Ensembl does NOT comsider NC_005089.1 (duplicate entry for MT) toplevel:
    mouse_chrom_info[mouse_chrom_info$SequenceName
    #            name length coord_system                      synonyms toplevel
    # 184 NC_005089.1  16299     scaffold                                  FALSE
    # 201          MT  16299   chromosome NC_005089.1, chrM, AY172335.1     TRUE
    #     SequenceName GenBankAccn  RefSeqAccn
    # 184           MT  AY172335.1 NC_005089.1
    # 201           MT  AY172335.1 NC_005089.1

    ## ------------------------------------------------------------------------
    ## Rat
    ## https://uswest.ensembl.org/Rattus_norvegicus/
    ## Based on Rnor_6.0 (GCA_000001895.4)

    # Return 1418 rows
    rat_chrom_info <- getChromInfoFromEnsembl("rnorvegicus")

    ## Map to NCBI
    ## Summary:
    ## - 955/955 NCBI sequences are reverse-mapped.
    ## - Reverse mapping is one-to-many: 2 Ensembl sequences (NC_001665.2 and MT)
    ##   are mapped to NCBI MT.
    Rnor_6.0 <- getChromInfoFromNCBI("Rnor_6.0")
    L2R <- map_to_NCBI(rat_chrom_info, Rnor_6.0)
    rat_chrom_info <- .do_join(rat_chrom_info, Rnor_6.0, L2R)

    ## Ensembl does NOT comsider NC_001665.2 (duplicate entry for MT) toplevel:
    rat_chrom_info[rat_chrom_info$SequenceName
    #             name length coord_system                      synonyms toplevel
    # 1417 NC_001665.2  16313     scaffold                                  FALSE
    # 1418          MT  16313   chromosome NC_001665.2, AY172581.1, chrM     TRUE
    #      SequenceName GenBankAccn  RefSeqAccn
    # 1417           MT  AY172581.1 NC_001665.2
    # 1418           MT  AY172581.1 NC_001665.2

    table(rat_chrom_info$SequenceRole, rat_chrom_info$toplevel)
    #                        FALSE TRUE
    #   assembled-molecule       1   23
    #   alt-scaffold             0    0
    #   unlocalized-scaffold     0  354
    #   unplaced-scaffold        0  578
    #   pseudo-scaffold          0    0
    #   fix-patch                0    0
    #   novel-patch              0    0

    ## End(Not run)

[Package GenomeInfoDb version 1.26.7 Index]