What are the common string processing methods in R language
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Basic string processing common in R language, involving matching, substitution, segmentation, interception, case conversion, etc.
A = c ("abcdgegh") B = c ("abcdgegh", "deghgabcd")
Match
Grep (pattern, x, ignore.case = FALSE, perl = FALSE, value = FALSE, fixed = FALSE, useBytes = FALSE, invert = FALSE) grepl (pattern, x, ignore.case = FALSE, perl = FALSE, fixed = FALSE, useBytes = FALSE) # # ignore.case determines whether the match is case-sensitive. In order to achieve accurate matching, the default is case-sensitive; you can set it to be insensitive
Grep () returns a matching result, where the invert setting returns a string on a match or an unmatched string, and grepl () returns a logical value, for example:
> grep ("ab", A) [1] 1 > grep ("ab", Bmaim valueholders) [1] "abcdgegh"deghgabcd" > grep ("de", Bmaejinghuo valueful) [1] "deghgabcd" > grep ("de", B Meijing valueholders) [1] "abcdgegh" # grepl string starting match can also be anchored with "^" > grepl ("ab", A) [1] TRUE > grepl ("ab", B) [1] TRUE TRUE
Match and replace
Sub (pattern, replacement, x, ignore.case = FALSE, perl = FALSE, fixed = FALSE, useBytes = FALSE) gsub (pattern, replacement, x, ignore.case = FALSE, perl = FALSE, fixed = FALSE, useBytes = FALSE) chartr (old, new, x)
Sub (), gsub (), chartr () can return the result after replacement
> sub ("ab", "AB", B) [1] "ABcdgegh"deghgABcd" > gsub ("ab", "AB", B) [1] "ABcdgegh"deghgABcd" > chartr ("a", "A", B) [1] "Abcdgegh"deghgAbcd"
Split, split, intercept
Strsplit (x, split, fixed = FALSE, perl = FALSE, useBytes = FALSE) substr (x, start, stop) substring (text, first, last = 1000000L)
For example:
> strsplit (A, "d") [[1]] [1] "abc", "gegh" > unlist (strsplit (A, "d")) [1] "abc", "gegh" > substr (A deg 1) [1] "abc" > substr (BMI 1 deg 3) [1] "abc", "deg" > substring (A Last 4) [1] "abcd" > substring (BJI Lasters 4) [1] "abcd"degh" >
Case replacement
# # replace with uppercase toupper (x) # # replace with lowercase tolower (x) # # convert uppercase and lowercase casefold according to parameters (xmeme uppercase false)
For example:
> toupper (A) [1] "ABCDGEGH" > tolower (toupper (A)) [1] "abcdgegh" > casefold (A heroin uppermost T) [1] "ABCDGEGH"
In addition, there is a character-specific package strngr that can perform a variety of operations on strings.
Package: stringr
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