Extract a substring from a string by picking up individual letters by their position.
A character vector, or an XString, XStringViews or MaskedXString object.
An integer vector with no NAs.
Unlike with the
i must contain valid positions.
A character vector of length 1 when
x is an XString
or MaskedXString object (the masks are ignored for the latter).
A character vector of the same length as
is a character vector or an XStringViews object.
Note that, because
i must contain valid positions,
all non-NA elements in the result are guaranteed to have exactly
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16
x <- c("abcd", "ABC") i <- c(3, 1, 1, 2, 1) ## With a character vector: letter(x, 3:1) letter(x, 3) letter(x, i) #letter(x, 4) # Error! ## With a BString object: letter(BString(x), i) # returns a character vector BString(x)[i] # returns a BString object ## With an XStringViews object: x2 <- as(BStringSet(x), "Views") letter(x2, i)
Loading required package: BiocGenerics Loading required package: parallel Attaching package: 'BiocGenerics' The following objects are masked from 'package:parallel': clusterApply, clusterApplyLB, clusterCall, clusterEvalQ, clusterExport, clusterMap, parApply, parCapply, parLapply, parLapplyLB, parRapply, parSapply, parSapplyLB The following objects are masked from 'package:stats': IQR, mad, sd, var, xtabs The following objects are masked from 'package:base': Filter, Find, Map, Position, Reduce, anyDuplicated, append, as.data.frame, cbind, colMeans, colSums, colnames, do.call, duplicated, eval, evalq, get, grep, grepl, intersect, is.unsorted, lapply, lengths, mapply, match, mget, order, paste, pmax, pmax.int, pmin, pmin.int, rank, rbind, rowMeans, rowSums, rownames, sapply, setdiff, sort, table, tapply, union, unique, unsplit, which, which.max, which.min Loading required package: S4Vectors Loading required package: stats4 Attaching package: 'S4Vectors' The following object is masked from 'package:base': expand.grid Loading required package: IRanges Loading required package: XVector Attaching package: 'Biostrings' The following object is masked from 'package:base': strsplit  "cba"  "c" "C"  "caaba" "CAABA"  "caaba" 5-letter "BString" instance seq: caaba  "caaba" "CAABA"
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.