I have the following data.table
library(data.table)
dt <- data.table(c('Female 18 - 24', 'Male 18+', 'People 18 -54'))
How can I transform it to
dt <- data.table(c('F 18 - 24', 'M 18+', 'P 18 -54')) using regex ?
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quant
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2 Answers
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gsub('(^[A-Z])[A-Za-z]+\\s(*.)','\\1 \\2',c('Female 18 - 24', 'Male 18+', 'People 18 -54'))
[1] "F 18 - 24" "M 18+" "P 18 -54"
(^[A-Z]) take the first letter as group1
[A-Za-z]+\\s any number of small letters follwed by a space
(*.) take any thing come after a space as group2
'\\1 \\2' Finally, return group1 and group2 separated by a space 
A. Suliman
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it worked. thanks. could you please provide some explanation also ? – quant Oct 24 '18 at 11:52
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1or `gsub("^(.)[^ ]* (.*)", "\\1 \\2", x)` – jogo Oct 24 '18 at 14:33
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require(data.table)
require(stringi)
dt <- data.table(V1=c('Female 18 - 24', 'Male 18+', 'People 18 -54'))
dt[,V2:= stri_replace_first_regex(V1,"(?<=\\w)\\w+","")]
dt
V1 V2
1: Female 18 - 24 F 18 - 24
2: Male 18+ M 18+
3: People 18 -54 P 18 -54
asepsiswu
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Don't use `require` when you just want to load the package. Use `library`. See [this SO answer](https://stackoverflow.com/questions/5595512/what-is-the-difference-between-require-and-library/51263513) for more details. – phiver Oct 27 '18 at 15:19