CODEWITHSUNDEEP
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Reputation: 57286

R - how to get a word in a specific location from a string?

How can I get a word in a specific location from a string?

For instance I want to get the station code in London, UK:

code <- getStationCode("London", region="UNITED KINGDOM")
code

Result:

[1] "UNITED KINGDOM    EGLINTON/LONDOND EGAE               55 02N  007 09W    9   X     T          6 GB"
[2] "UNITED KINGDOM    LONDON/GATWICK A EGKK        03776  51 08N  000 10W   62   X     T          6 GB"
[3] "UNITED KINGDOM    LONDON CITY AIRP EGLC               51 30N  000 03E    5   X     T          6 GB"
[4] "UNITED KINGDOM    LONDON/HEATHROW  EGLL        03772  51 29N  000 27W   24   X     T          6 GB"
[5] "UNITED KINGDOM    LONDON WEA CENTE EGRB        03779  51 30N  000 07W   39   X                7 GB"

For instance I select the second item in the list:

second <- code[2]

I will get:

"UNITED KINGDOM    LONDON/GATWICK A EGKK        03776  51 08N  000 10W   62   X     T          6 GB"

Then how can I get EGKK from that string?

Upvotes: 1

Views: 122

Answers (1)

akrun
akrun

Reputation: 887971

We can use str_extract to extract one or more upper case letters followed by regex lookaround (one or more spaces (\\s+) followed by one or more numbers ([0-9]+))

library(stringr)
str_extract(str1, "[A-Z]+(?=\\s+[0-9]+)")
#[1] "EGKK"

If the Station codes are 4 letter strings

str_extract(str1, "\\b[A-Z]{4}\\b")
#[1] "EGKK"

data

str1 <- "UNITED KINGDOM    LONDON/GATWICK A EGKK        03776  51 08N  000 10W   62   X     T          6 GB"

Upvotes: 3

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