r - return column index condition on column names -


i have data frame named dat. has columns prefix vix.

eg.

date, vo, vix2, vix3, vix4, ... vix24, other columns

in case,

start = which(names(dat) == "vix2")

end = which(names(dat) == "vix24")

but problem is, don't know number arrangement after vix. in case, there way return start , end?

you can try

 range(grep('vix', names(dat)))

suppose if columns not consecutive

  v1 <- c('date',  'vix2',  'v0', 'vix3', 'v5', 'vix4')   range(grep('vix', v1))   #[1] 2 6

will give first , last entry 'vix', if going subset dataset 'vix' columns, don't need range, grep enough

  grep('vix', v1)  #[1] 2 4 6

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