在r中的两个“-”之间提取字符串

Question

I am trying to understand how do i extract the string which is between two hyphens.

For example,

node->testtransport-fasttrack-direct

I want the string fasttrack to be extracted and it shouldnt be based on the position of the strings as they might change.

I want the hard code to extract the string present between two hyphens

Thank you in advance.

Answer 1

Here are some approaches. No packages are used.

1) Here we assume that the part between the two minus signs must be all upper case letters so >DHLPAKET is excluded because even though it is between two minus signs it has a character which is not an upper case letter. Match the start (^) and then anything (.*) followed by minus (-) followed by an upper case string which is captured ([AZ]+) and another minus (-) and everything else and finally the end of string ($). Replace all that with the captured portion (\\1)

x <- "WRO2->DHLPAKET-ASCHHEIM-DI"
sub("^.*-([A-Z]+)-.*$", "\\1", x)
## [1] "ASCHHEIM"

2) If the two minus signs surrounding the string of interest are always the second and third minus signs then this would work. It uses read.table picking off the third minus-separated field.

read.table(text = x, sep = "-", as.is = TRUE)$V3
## [1] "ASCHHEIM"