I am very much a novice with regular expressions and I have spent a decent amount of time trying to do the following and I can't get it. i have variables that are of type character but they have number characters at the end. for example : "AAL123" "XELB245" "A247" I want a command that gives me just gives me the letter characters for each one. the letter characters always start first and then the number characters come second and it never flips back to letter characters once the number characters start. i am using R-2.20 on windows Xp. Thanks. substring doesn't work because the length of the letter characters can vary. always occur first with the numbers starting
On 11 June 2006 at 14:25, markleeds at verizon.net wrote: | i have variables that are of type character but | they have number characters at the end. for example : | | "AAL123" | "XELB245" | "A247" | | I want a command that gives me just gives me the letter characters | for each one. | the letter characters always start first and then the number characters come second and it never flips back to letter characters | once the number characters start. i am using R-2.20 on | windows Xp. Thanks. substring doesn't work because the | length of the letter characters can vary.> gsub("(\\d*)$","",c("AAL123", "XELB245", "A247", "FOO123BAR"), perl=TRUE)[1] "AAL" "XELB" "A" "FOO123BAR">gsub finds what is described by the first regexp [ here (\\d\*)$ --- any sequence of digits before the end-of-line ] and applies the second regexp [ here an empty string as we simply delete ] to the third argument. Note - how the $ symbol $ \b prevents it from eating the non-final digits in the counter example FOO123BAR - how the \d for digits needs escaped backslashes \\d - how the * char denotes '1 or more of the preceding thingie' Hth, Dirk -- Hell, there are no rules here - we're trying to accomplish something. -- Thomas A. Edison
This will delete numbers at the end:
sub("[0-9]+$", "", c("AAL123",
"XELB245", "A247"))
If you want remove all numbers its just:
gsub("[0-9]", "", c("AAL123", "XELB245",
"A247"))
On 6/11/06, markleeds at verizon.net <markleeds at verizon.net>
wrote:> I am very much a novice with regular expressions and I have spent
> a decent amount of time trying to do the following and I can't
> get it.
>
> i have variables that are of type character but
> they have number characters at the end. for example :
>
> "AAL123"
> "XELB245"
> "A247"
>
> I want a command that gives me just gives me the letter characters
> for each one.
> the letter characters always start first and then the number characters
come second and it never flips back to letter characters
> once the number characters start. i am using R-2.20 on
> windows Xp. Thanks. substring doesn't work because the
> length of the letter characters can vary.
>
>
> always occur first with the numbers starting
>
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