Fixing Character Vectors
Fix the case of character vectors using tolower() and toupper().
Split up a word using strsplit()
string_to_split <- c('this.1', 'something.2', 'another')
strsplit(string_to_split, '\\.')## [[1]]
## [1] "this" "1"
##
## [[2]]
## [1] "something" "2"
##
## [[3]]
## [1] "another"Substitute out characters using the sub() function.
strings_to_sub <- c('this-is-going-to', 'replace-some', 'hyphens')
# sub replaces only the first instance
sub('-', '_', strings_to_sub)## [1] "this_is-going-to" "replace_some" "hyphens"# gsub replaces all instances
gsub('-', '_', strings_to_sub)## [1] "this_is_going_to" "replace_some" "hyphens"Use grep() and grepl() to find values. grep() returns a vector of the matching indicies, and grepl() returns a logical vector of matches and not matches.
greppable <- c('these', 'are', 'some', 'words', 'to', 'grep')
# Return indicies
grep('to', greppable)## [1] 5# Return a logical vector
grepl('o', greppable)## [1] FALSE FALSE TRUE TRUE TRUE FALSE#Return the values
grep('[swt]o', greppable, value = T)## [1] "some" "words" "to"Working with Dates
Dates
Date function:
d1 <- date()
d1## [1] "Fri Oct 25 06:52:04 2019"class(d1)## [1] "character"d2 <- Sys.Date()
d2## [1] "2019-10-25"class(d2)## [1] "Date"Use the format() function to alter the format of the date.
format(d2, "%A %d %B %Y")## [1] "Friday 25 October 2019"To create a date, use the as.Date() function.
some_dates <- c('01oct1990', '02sep1991')
d3 <- as.Date(some_dates, '%d%b%Y')
weekdays(d3)## [1] "Monday" "Monday"The Lubridate package is very good when working with dates / times.
library(lubridate)##
## Attaching package: 'lubridate'## The following object is masked from 'package:base':
##
## dateymd('19200202')## [1] "1920-02-02"dmy('01-01-2001')## [1] "2001-01-01"Times
Lubridate also has functions for working with times.
ymd_hms('2002-01-01 14:01:01')## [1] "2002-01-01 14:01:01 UTC"ymd_hms('2002-01-01 14:01:01', tz = 'Australia/Melbourne')## [1] "2002-01-01 14:01:01 AEDT"