integer-utils {S4Vectors} | R Documentation

## Some utility functions to operate on integer vectors

### Description

Some low-level utility functions to operate on ordinary integer vectors.

### Usage

    isSequence(x, of.length=length(x))

    toListOfIntegerVectors(x, sep=",")

    ## more to come...

### Arguments

`x` | For `isSequence()`: An integer vector. For `toListOfIntegerVectors()`: A character vector where each element is a string containing comma-separated integers in decimal representation. Alternatively `x` can be a list of raw vectors, in which case it's treated like if it was `sapply(x, rawToChar)`.
`of.length` | The expected length of the integer sequence.
`sep` | The separator represented as a single-letter string.

### Details

`isSequence()` returns `TRUE` or `FALSE` depending on whether `x` is identical to `seq_len(of.length)` or not.

`toListOfIntegerVectors()` is a fast and memory-efficient implementation of

        lapply(strsplit(x, sep, fixed=TRUE), as.integer)

but, unlike the above code, it will raise an error if the input contains NAs or strings that don't represent integer values.

### Value

A list parallel to `x` where each list element is an integer vector.

### Author(s)

Hervé Pagès

### See Also

- The `seq_len` function in the base package.

- The `strsplit` function in the base package.

### Examples

    ## ---------------------------------------------------------------------
    ## isSequence()
    ## ---------------------------------------------------------------------
    isSequence(1:5)               # TRUE
    isSequence(5:1)               # FALSE
    isSequence(0:5)               # FALSE
    isSequence(integer(0))        # TRUE
    isSequence(1:5, of.length=5)  # TRUE (the expected length)
    isSequence(1:5, of.length=6)  # FALSE (not the expected length)

    ## ---------------------------------------------------------------------
    ## toListOfIntegerVectors()
    ## ---------------------------------------------------------------------

    x <- c("1116,0,-19",
           " +55291 , 2476,",
           "19184,4269,5659,6470,6721,7469,14601",
           "7778889, 426900, -4833,5659,6470,6721,7096",
           "19184 , -99999")

    y <- toListOfIntegerVectors(x)
    y

    ## When it doesn't choke on an NA or string that doesn't represent
    ## an integer value, toListOfIntegerVectors() is equivalent to
    ## the function below but is faster and more memory-efficient:
    toListOfIntegerVectors2 <- function(x, sep=",")
    {
        lapply(strsplit(x, sep, fixed=TRUE), as.integer)
    }
    y2 <- toListOfIntegerVectors2(x)
    stopifnot(identical(y, y2))

[Package S4Vectors version 0.20.1 Index]