Order or Sort Strings With Embedded Numbers So That The Numbers Are In The Correct Order

Description

These functions sort or order character strings containing numbers so that the numbers are numerically sorted rather than sorted by character value. I.e. "Asprin 50mg" will come before "Asprin 100mg". In addition, case of character strings is ignored so that "a", will come before "B" and "C".

Usage

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SortMixed(x)

Arguments

x

Character vector to be sorted

Details

I often have character vectors (e.g. factor labels) that contain both text and numeric data, such as compound and dose. This function is useful for sorting these character vectors into a logical order.

It does so by splitting each character vector into a sequence of character and numeric sections, and then sorting along these sections, with numbers being sorted by numeric value (e.g. "50" comes before "100"), followed by characters strings sorted by character value (e.g. "A" comes before "B").

Empty strings are always sorted to the front of the list, and NA values to the end.

Value

OrderMixed returns a vector giving the sort order of the input elements. SortMixed returns the sorted vector.

Author(s)

Gregory R. Warnes <greg@warnes.net>

See Also

sort, order

Examples

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# compound & dose labels
Treatment <- c("Control", "Asprin 10mg/day", "Asprin 50mg/day",
               "Asprin 100mg/day", "Acetomycin 100mg/day",
               "Acetomycin 1000mg/day")

# ordinary sort puts the dosages in the wrong order
sort(Treatment)

# but SortMixed does the 'right' thing
SortMixed(Treatment)

# Here is a more complex example
x <- rev(c("AA 0.50 ml", "AA 1.5 ml", "AA 500 ml", "AA 1500 ml",
           "EXP 1", "AA 1e3 ml", "A A A", "1 2 3 A", "NA", NA, "1e2",
           "", "-", "1A", "1 A", "100", "100A", "Inf"))

OrderMixed(x)

SortMixed(x)
# notice that plain numbers, including 'Inf' show up before strings.

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