Use any occurrence of one or more digits as a separator?
s <- c( "CCl3F", "Li4Al4H16", "CCl2CO2AlPO4SiO4Cl" )
strsplit( s, "\\d+" )
On October 18, 2023 7:59:01 AM PDT, Leonard Mada via R-help
<r-help@r-project.org> wrote:
>Dear List members,
>
>What is the best way to test for numeric digits?
>
>suppressWarnings(as.double(c("Li", "Na", "K", "2", "Rb", "Ca", "3")))
># [1] NA NA NA 2 NA NA 3
>The above requires the use of the suppressWarnings function. Are there any
>better ways?
>
>I was working to extract chemical elements from a formula, something like this:
>split.symbol.character = function(x, rm.digits = TRUE) {
> # Perl is partly broken in R 4.3, but this works:
> regex = "(?<=[A-Z])(?![a-z]|$)|(?<=.)(?=[A-Z])|(?<=[a-z])(?=[^a-z])";
> # stringi::stri_split(x, regex = regex);
> s = strsplit(x, regex, perl = TRUE);
> if(rm.digits) {
> s = lapply(s, function(s) {
> isNotD = is.na(suppressWarnings(as.numeric(s)));
> s = s[isNotD];
> });
> }
> return(s);
>}
>
>split.symbol.character(c("CCl3F", "Li4Al4H16", "CCl2CO2AlPO4SiO4Cl"))
>
>
>Sincerely,
>
>
>Leonard
>
>
>Note:
># works:
>regex = "(?<=[A-Z])(?![a-z]|$)|(?<=.)(?=[A-Z])|(?<=[a-z])(?=[^a-z])";
>strsplit(c("CCl3F", "Li4Al4H16", "CCl2CO2AlPO4SiO4Cl"), regex, perl = T)
>
>
># broken in R 4.3.1
># only slightly "erroneous" with stringi::stri_split
>regex = "(?<=[A-Z])(?![a-z]|$)|(?=[A-Z])|(?<=[a-z])(?=[^a-z])";
>strsplit(c("CCl3F", "Li4Al4H16", "CCl2CO2AlPO4SiO4Cl"), regex, perl = T)
>
>______________________________________________
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>PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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--
Sent from my phone. Please excuse my brevity.
______________________________________________
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
