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OrganismDbi is a software package that helps tie together different annotation resources. It is expected that users may have previously made or seen packages like org.Hs.eg.db and TxDb.Hsapiens.UCSC.hg19.knownGene. Packages like these two are very different and contain very different kinds of information, but are still about the same organism: Homo sapiens. The OrganismDbi package allows us to combine resources like these together into a single package resource, which can represent ALL of these resources at the same time. An example of this is the Homo.sapiens package, which combines access to the two resources above along with others.

This is made possible because the packages that are represented by Homo.sapiens are related to each other via foreign keys.

Relationships between Annotation packages

Figure 1: Relationships between Annotation packages

1 Getting started with OrganismDbi

Usage of a package like this has been deliberately kept very simple. The methods supported are the same ones that work for all the packages based on AnnotationDb objects. The methods that can be applied to these new packages are columns, keys, keytypes and select.

So to learn which kinds of data can be retrieved from a package like this we would simply load the package and then call the columns method.

library(Homo.sapiens)
columns(Homo.sapiens)
##  [1] "ACCNUM"       "ALIAS"        "CDSCHROM"     "CDSEND"       "CDSID"       
##  [6] "CDSNAME"      "CDSPHASE"     "CDSSTART"     "CDSSTRAND"    "DEFINITION"  
## [11] "ENSEMBL"      "ENSEMBLPROT"  "ENSEMBLTRANS" "ENTREZID"     "ENZYME"      
## [16] "EVIDENCE"     "EVIDENCEALL"  "EXONCHROM"    "EXONEND"      "EXONID"      
## [21] "EXONNAME"     "EXONRANK"     "EXONSTART"    "EXONSTRAND"   "GENEID"      
## [26] "GENENAME"     "GENETYPE"     "GO"           "GOALL"        "GOID"        
## [31] "IPI"          "MAP"          "OMIM"         "ONTOLOGY"     "ONTOLOGYALL" 
## [36] "PATH"         "PFAM"         "PMID"         "PROSITE"      "REFSEQ"      
## [41] "SYMBOL"       "TERM"         "TXCHROM"      "TXEND"        "TXID"        
## [46] "TXNAME"       "TXSTART"      "TXSTRAND"     "TXTYPE"       "UCSCKG"      
## [51] "UNIPROT"

To learn which of those kinds of data can be used as keys to extract data, we use the keytypes method.

keytypes(Homo.sapiens)
##  [1] "ACCNUM"       "ALIAS"        "CDSID"        "CDSNAME"      "DEFINITION"  
##  [6] "ENSEMBL"      "ENSEMBLPROT"  "ENSEMBLTRANS" "ENTREZID"     "ENZYME"      
## [11] "EVIDENCE"     "EVIDENCEALL"  "EXONID"       "EXONNAME"     "GENEID"      
## [16] "GENENAME"     "GENETYPE"     "GO"           "GOALL"        "GOID"        
## [21] "IPI"          "MAP"          "OMIM"         "ONTOLOGY"     "ONTOLOGYALL" 
## [26] "PATH"         "PFAM"         "PMID"         "PROSITE"      "REFSEQ"      
## [31] "SYMBOL"       "TERM"         "TXID"         "TXNAME"       "UCSCKG"      
## [36] "UNIPROT"

To extract specific keys, we need to use the keys method, and also provide it a legitimate keytype:

head(keys(Homo.sapiens, keytype = "ENTREZID"))
## [1] "1"  "2"  "9"  "10" "11" "12"

And to extract data, we can use the select method. The select method depends on the values from the previous three methods to specify what it will extract. Here is an example that will extract, UCSC transcript names, and gene symbols using Entrez Gene IDs as keys.

k <- head(keys(Homo.sapiens, keytype = "ENTREZID"), n = 3)
select(
  Homo.sapiens,
  keys = k,
  columns = c("TXNAME", "SYMBOL"),
  keytype = "ENTREZID"
)
##    ENTREZID SYMBOL               TXNAME
## 1         1   A1BG  ENST00000596924.1_3
## 2         1   A1BG  ENST00000263100.8_8
## 3         1   A1BG  ENST00000850949.1_1
## 4         1   A1BG  ENST00000850950.1_1
## 5         1   A1BG  ENST00000600123.5_4
## 6         1   A1BG  ENST00000595014.1_3
## 7         1   A1BG  ENST00000598345.2_4
## 8         1   A1BG  ENST00000599109.5_5
## 9         1   A1BG  ENST00000600966.1_7
## 10        1   A1BG  ENST00000596636.1_3
## 11        2    A2M  ENST00000543436.2_3
## 12        2    A2M ENST00000318602.12_7
## 13        2    A2M  ENST00000495442.1_3
## 14        2    A2M  ENST00000495709.1_3
## 15        2    A2M  ENST00000545828.1_3
## 16        2    A2M  ENST00000542567.1_3
## 17        2    A2M  ENST00000462568.1_3
## 18        2    A2M  ENST00000546069.1_4
## 19        2    A2M  ENST00000472360.1_3
## 20        2    A2M  ENST00000539638.5_4
## 21        2    A2M  ENST00000404455.2_7
## 22        2    A2M  ENST00000467091.1_3
## 23        2    A2M  ENST00000497324.1_3
## 24        9   NAT1  ENST00000517441.5_1
## 25        9   NAT1  ENST00000307719.9_4
## 26        9   NAT1  ENST00000518029.5_1
## 27        9   NAT1  ENST00000517574.5_1
## 28        9   NAT1  ENST00000519006.5_1
## 29        9   NAT1  ENST00000545197.3_2
## 30        9   NAT1  ENST00000517492.5_1
## 31        9   NAT1  ENST00000520546.1_1

In addition to select, some of the more popular range based methods have also been updated to work with an AnnotationDb object. So for example you could extract transcript information like this:

transcripts(Homo.sapiens, columns = c("TXNAME", "SYMBOL"))
## GRanges object with 381987 ranges and 2 metadata columns:
##            seqnames      ranges strand |              TXNAME          SYMBOL
##               <Rle>   <IRanges>  <Rle> |     <CharacterList> <CharacterList>
##        [1]     chr1 10370-10582      + | ENST00000833856.1_2            <NA>
##        [2]     chr1 11121-14413      + | ENST00000832824.1_1         DDX11L1
##        [3]     chr1 11125-14405      + | ENST00000832825.1_1         DDX11L1
##        [4]     chr1 11410-14413      + | ENST00000832826.1_1         DDX11L1
##        [5]     chr1 11411-14413      + | ENST00000832827.1_1         DDX11L1
##        ...      ...         ...    ... .                 ...             ...
##   [381983]    chrMT   5826-5891      - |   ENST00000387409.1            <NA>
##   [381984]    chrMT   7446-7514      - |   ENST00000387416.2            <NA>
##   [381985]    chrMT 14149-14673      - | ENST00000361681.2_5            <NA>
##   [381986]    chrMT 14674-14742      - |   ENST00000387459.1            <NA>
##   [381987]    chrMT 15956-16023      - |   ENST00000387461.2            <NA>
##   -------
##   seqinfo: 298 sequences (2 circular) from hg19 genome

And the GRanges object that would be returned would have the information that you specified in the columns argument. You could also have used the exons or cds methods in this way.

The transcriptsBy,exonsBy and cdsBy methods are also supported. For example:

transcriptsBy(Homo.sapiens,
              by = "gene",
              columns = c("TXNAME", "SYMBOL"))
## GRangesList object of length 28646:
## $`1`
## GRanges object with 10 ranges and 3 metadata columns:
##        seqnames            ranges strand |             tx_name
##           <Rle>         <IRanges>  <Rle> |         <character>
##    [1]    chr19 58856544-58859000      - | ENST00000596924.1_3
##    [2]    chr19 58856549-58864858      - | ENST00000263100.8_8
##    [3]    chr19 58856549-58864858      - | ENST00000850949.1_1
##    [4]    chr19 58856549-58864858      - | ENST00000850950.1_1
##    [5]    chr19 58858220-58867591      - | ENST00000600123.5_4
##    [6]    chr19 58858224-58864857      - | ENST00000595014.1_3
##    [7]    chr19 58858226-58859023      - | ENST00000598345.2_4
##    [8]    chr19 58859832-58874117      - | ENST00000599109.5_5
##    [9]    chr19 58861960-58864495      - | ENST00000600966.1_7
##   [10]    chr19 58864387-58867449      - | ENST00000596636.1_3
##                     TXNAME          SYMBOL
##            <CharacterList> <CharacterList>
##    [1] ENST00000596924.1_3            A1BG
##    [2] ENST00000263100.8_8            A1BG
##    [3] ENST00000850949.1_1            A1BG
##    [4] ENST00000850950.1_1            A1BG
##    [5] ENST00000600123.5_4            A1BG
##    [6] ENST00000595014.1_3            A1BG
##    [7] ENST00000598345.2_4            A1BG
##    [8] ENST00000599109.5_5            A1BG
##    [9] ENST00000600966.1_7            A1BG
##   [10] ENST00000596636.1_3            A1BG
##   -------
##   seqinfo: 298 sequences (2 circular) from hg19 genome
## 
## $`10`
## GRanges object with 2 ranges and 3 metadata columns:
##       seqnames            ranges strand |             tx_name
##          <Rle>         <IRanges>  <Rle> |         <character>
##   [1]     chr8 18248792-18258728      + | ENST00000286479.4_4
##   [2]     chr8 18248797-18258503      + | ENST00000520116.1_2
##                    TXNAME          SYMBOL
##           <CharacterList> <CharacterList>
##   [1] ENST00000286479.4_4            NAT2
##   [2] ENST00000520116.1_2            NAT2
##   -------
##   seqinfo: 298 sequences (2 circular) from hg19 genome
## 
## ...
## <28644 more elements>

2 Making your own OrganismDbi packages

So in the preceding section you can see that using an OrganismDbi package behaves very similarly to how you might use a TxDb or an OrgDb package. The same methods are defined, and they behave similarly except that they now have access to much more data than before. But before you make your own OrganismDbi package you need to understand that there are few logical limitations for what can be included in this kind of package.

With these limitations in mind, lets set up an example. Lets show how we could make Homo.sapiens, such that it allowed access to org.Hs.eg.db, TxDb.Hsapiens.UCSC.hg19.knownGene and GO.db.

The 1st thing that we need to do is set up a list that expresses the way that these different packages relate to each other. To do this, we make a list that contains short two element long character vectors. Each character vector represents one relationship between a pair of packages. The names of the vectors are the package names and the values are the foreign keys. Please note that the foreign key values in these vectors are the same strings that are returned by the columns method for the individual packages. Here is an example that shows how GO.db, org.Hs.eg.db and TxDb.Hsapiens.UCSC.hg19.knownGene all relate to each other.

gd <- list(
  join1 = c(GO.db = "GOID", org.Hs.eg.db = "GO"),
  join2 = c(
    org.Hs.eg.db = "ENTREZID",
    TxDb.Hsapiens.UCSC.hg19.knownGene = "GENEID"
  )
)

So this data.frame indicates both which packages are connected to each other, and also what these connections are using for foreign keys. Once this is finished, we just have to call the makeOrganismPackage function to finish the task.

destination <- tempfile()
dir.create(destination)
makeOrganismPackage(
  pkgname = "Homo.sapiens",
  graphData = gd,
  organism = "Homo sapiens",
  version = "1.0.0",
  maintainer = "Package Maintainer<maintainer@somewhere.org>",
  author = "Some Body",
  destDir = destination,
  license = "Artistic-2.0"
)

makeOrganismPackage will then generate a lightweight package that you can install. This package will not contain all the data that it refers to, but will instead depend on the packages that were referred to in the data.frame. Because the end result will be a package that treats all the data mapped together as a single source, the user is encouraged to take extra care to ensure that the different packages used are from the same build etc.