This page includes all the material you need to deal with strings in R. The section on regular expressions may be useful to understand the rest of the page, even if it is not necessary if you only need to perform some simple tasks.<\/p>\n
This page may be useful to\u00a0:<\/p>\n
In this page, we learn how to read a text file and how to use R functions for characters. There are two kind of function for characters, simple functions and regular expressions. Many functions are part of the standard R base<\/b> package.<\/p>\n However, their name and their syntax is not intuitive to all users. Hadley Wickham has developed the stringr<\/b> package which defines functions with similar behaviour but their names are easier to retain and their syntax much more systematic[1]<\/a><\/sup>.<\/p>\n \u00a0[hide<\/a>]\u00a0<\/span><\/div>\n R<\/b> can read any text file using help.search<\/span><\/span>(<\/span>keyword =<\/span> \"character\"<\/span>, package =<\/span> \"base\"<\/span>)<\/span>\n<\/pre>\n<\/div>\n<\/div>\n\n
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Reading and writing text files<\/span>[<\/span>edit<\/a>]<\/span><\/span><\/h2>\n
readLines()<\/code> or scan()<\/code>. It is possible to specify the encoding of the imported text file with readLines()<\/code>. The entire contents of the text file can be read into an R object (e.g., a character vector). scan()<\/code> is more flexible. The kind of data expected can be specified in the second argument (e.g., character(0) for a string).<\/p>\ntext<\/span> <-<\/span> readLines<\/span>(<\/span>\"file.txt\"<\/span>,encoding=<\/span>\"UTF-8\"<\/span>)<\/span>\nscan<\/span>(<\/span>\"file.txt\"<\/span>, character<\/span>(<\/span>0<\/span>)<\/span>)<\/span> # separate each word<\/span>\nscan<\/span>(<\/span>\"file.txt\"<\/span>, character<\/span>(<\/span>0<\/span>)<\/span>, quote<\/span> =<\/span> NULL)<\/span> # get rid of quotes<\/span>\nscan<\/span>(<\/span>\"file.txt\"<\/span>, character<\/span>(<\/span>0<\/span>)<\/span>, sep =<\/span> \".\"<\/span>)<\/span> # separate each sentence<\/span>\nscan<\/span>(<\/span>\"file.txt\"<\/span>, character<\/span>(<\/span>