Strings

Rory Nolan

2017-02-23

Please Read the Manual

This package is one for which the functions are largely simple enough such that the function names well describe their purpose, so the manual is an excellent way to acquaint yourself with the package. But I made a couple of vignettes anyway.

First let’s load the library:

library(filesstrings)

Here are some string operations that I wished were easier in R.

The nth number in a string

I often want to get the first, last or nth number in a string.

request <- "I want the $35 scarf."
NthNumber(request, 1)
#> [1] 35
NthNumber("20 people want the $12 scarf.", -1)  # last number
#> [1] 12
GetCurrency(request)
#> [1] "$"

Messed up file numbering

The microscope I use numbers files with 3 numbers by default, i.e. file001.tif, file002.tif and so on. This is a problem when the automatic numbering passes 1000, whereby we have file999.tif, file1000.tif. What’s the problem with this? Well, sometimes you need alphabetical order to reflect the true order of your files. These file numbers don’t satisfy this requirement:

file.names <- c("file999.tif", "file1000.tif")
sort(file.names)
#> [1] "file1000.tif" "file999.tif"

so file1000.tif comes before file999.tif in alphabetical order. We want them to be like

NiceNums(file.names)
#> [1] "file0999.tif" "file1000.tif"

The function NiceFileNums renames all the files in an entire directory to be as we would like. It wraps NiceNums.

Could that be interpreted as numeric?

Sometimes we don’t want to know is something is numeric, we want to know if it could be considered to be numeric (or could be coerced to numeric).

is.numeric(23)
#> [1] TRUE
is.numeric("23")
#> [1] FALSE
CanBeNumeric(23)
#> [1] TRUE
CanBeNumeric("23")
#> [1] TRUE
CanBeNumeric("23a")
#> [1] FALSE
StrSplitByNums("23a")
#> [[1]]
#> [1] "23" "a"
CanBeNumeric(StrSplitByNums("23a")[[1]])
#> [1]  TRUE FALSE

The name of a file without the extension

BeforeLastDot("spreadsheet_92.csv")
#> spreadsheet_92.csv 
#>   "spreadsheet_92"

Get the nth element of a string

StrElem("abc", 2)
#> [1] "b"
StrElem("abcdefz", -1)
#> [1] "z"