seqApply {SeqArray} | R Documentation

## Apply Functions Over Array Margins

### Description

Returns a vector or list of values obtained by applying a function to margins of genotypes and annotations.

### Usage

    seqApply(gdsfile, var.name, FUN, margin=c("by.variant", "by.sample"),
        as.is=c("none", "list", "integer", "double", "character", "logical", "raw"),
        var.index=c("none", "relative", "absolute"), parallel=FALSE,
        .useraw=FALSE, .progress=FALSE, .list_dup=TRUE, ...)

### Arguments

`gdsfile` | a `SeqVarGDSClass` object
`var.name` | the variable name(s), see details
`FUN` | the function to be applied
`margin` | giving the dimension which the function will be applied over
`as.is` | returned value: a list, an integer vector, etc; `as.is` can be a `connection` object, or a GDS node `gdsn.class` object; if "unlist" is used, produces a vector which contains all the atomic components, via `unlist(..., recursive=FALSE)`
`var.index` | if `"none"`, call `FUN(x, ...)` without variable index; if `"relative"` or `"absolute"`, add an argument to the user-defined function `FUN` like `FUN(index, x, ...)` where `index` is an index of variant starting from 1 if `margin = "by.variant"`: `"relative"` for indexing in the selection defined by `seqSetFilter`, `"absolute"` for indexing with respect to all data
`parallel` | `FALSE` (serial processing), `TRUE` (multicore processing), numeric value or other value; `parallel` is passed to the argument `cl` in `seqParallel`, see `seqParallel` for more details.
`.useraw` | `TRUE`, force to use RAW instead of INTEGER for genotypes and dosages; `FALSE`, use INTEGER; `NA`, use RAW for small numbers instead of INTEGER if possible, it is needed to detect data type (RAW or INTEGER) in the user-defined function; for genotypes, 0xFF is missing value if RAW is used
`.progress` | if `TRUE`, show progress information
`.list_dup` | internal use only
`...` | optional arguments to `FUN`

### Details

The variable name should be `"sample.id"`, `"variant.id"`, `"position"`, `"chromosome"`, `"allele"`, `"genotype"`, `"annotation/id"`, `"annotation/qual"`, `"annotation/filter"`, `"annotation/info/VARIABLE_NAME"`, or `"annotation/format/VARIABLE_NAME"`.

`"@genotype"`, `"annotation/info/@VARIABLE_NAME"` or `"annotation/format/@VARIABLE_NAME"` are used to obtain the index associated with these variables.

`"$dosage"` is also allowed for the dosages of reference allele (integer: 0, 1, 2 and NA for diploid genotypes).

`"$dosage_alt"` returns a RAW/INTEGER matrix for the dosages of alternative allele without distinguishing different alternative alleles.

`"$num_allele"` returns an integer vector with the numbers of distinct alleles.

`"$ref"` returns a character vector of reference alleles

`"$alt"` returns a character vector of alternative alleles (delimited by comma)

`"$chrom_pos"` returns characters with the combination of chromosome and position, e.g., "1:1272721". `"$chrom_pos_allele"` returns characters with the combination of chromosome, position and alleles, e.g., "1:1272721_A_G" (i.e., chr:position_REF_ALT).

The algorithm is highly optimized by blocking the computations to exploit the high-speed memory instead of disk.

### Value

A vector, a list of values or none.

### Author(s)

Xiuwen Zheng

### See Also

`seqBlockApply`, `seqSetFilter`, `seqGetData`, `seqParallel`, `seqGetParallel`

### Examples

    # the GDS file
    (gds.fn <- seqExampleFileName("gds"))

    # display
    (f <- seqOpen(gds.fn))

    # get 'sample.id
    (samp.id <- seqGetData(f, "sample.id"))
    # "NA06984" "NA06985" "NA06986" ...

    # get 'variant.id'
    head(variant.id <- seqGetData(f, "variant.id"))

    # set sample and variant filters
    set.seed(100)
    seqSetFilter(f, sample.id=samp.id[c(2,4,6,8,10)],
        variant.id=sample(variant.id, 10))

    # read
    seqApply(f, "genotype", FUN=print, margin="by.variant")
    seqApply(f, "genotype", FUN=print, margin="by.variant", .useraw=TRUE)

    seqApply(f, "genotype", FUN=print, margin="by.sample")
    seqApply(f, "genotype", FUN=print, margin="by.sample", .useraw=TRUE)

    # read multiple variables variant by variant
    seqApply(f, c(geno="genotype", phase="phase", rsid="annotation/id",
        DP="annotation/format/DP"), FUN=print, as.is="none")

    # get the numbers of alleles per variant
    seqApply(f, "allele",
        FUN=function(x) length(unlist(strsplit(x,","))), as.is="integer")

    # output to a file
    fl <- file("tmp.txt", "wt")
    seqApply(f, "genotype", FUN=sum, na.rm=TRUE, as.is=fl)
    close(fl)
    readLines("tmp.txt")

    seqApply(f, "genotype", FUN=sum, na.rm=TRUE, as.is=stdout())
    seqApply(f, "genotype", FUN=sum, na.rm=TRUE, as.is="integer")
    # should be identical

    ################################################################
    # with an index of variant

    seqApply(f, c(geno="genotype", phase="phase", rsid="annotation/id"),
        FUN=function(index, x) { print(index); print(x); index },
        as.is="integer", var.index="relative")
    # it is as the same as
    which(seqGetFilter(f)$variant.sel)

    ################################################################
    # reset sample and variant filters
    seqResetFilter(f)

    # calculate the frequency of reference allele,
    #   a faster version could be obtained by C coding
    af <- seqApply(f, "genotype", FUN=function(x) mean(x==0L, na.rm=TRUE),
        as.is="double")
    length(af)
    summary(af)

    ################################################################
    # apply the user-defined function sample by sample

    # reset sample and variant filters
    seqResetFilter(f)
    summary(seqApply(f, "genotype", FUN=function(x) { mean(is.na(x)) },
        margin="by.sample", as.is="double"))

    # set sample and variant filters
    set.seed(100)
    seqSetFilter(f, sample.id=samp.id[c(2,4,6,8,10)],
        variant.id=sample(variant.id, 10))

    seqApply(f, "genotype", FUN=print, margin="by.variant", as.is="none")

    seqApply(f, "genotype", FUN=print, margin="by.sample", as.is="none")

    seqApply(f, c(sample.id="sample.id", genotype="genotype"), FUN=print,
        margin="by.sample", as.is="none")

    # close the GDS file
    seqClose(f)

    # delete the temporary file
    unlink("tmp.txt")

[Package SeqArray version 1.22.6 Index]