How to extract first string in R

amisos55 0
Viewed 53

I have a regex question.

I have a list of files below.

df <- c("Alilis CELF-4_CF_Data_Entry.xlsx" , "Ana T. CELF-4_CF_Data_Entry.xlsx" , "Ana V. CELF-4_CF_Data_Entry.xlsx","Anita CELF-4_CF_Data_Entry.xlsx")

[1] "Alilis CELF-4_CF_Data_Entry.xlsx" "Ana T. CELF-4_CF_Data_Entry.xlsx" "Ana V. CELF-4_CF_Data_Entry.xlsx" "Anita CELF-4_CF_Data_Entry.xlsx"

I need to extract the name at the beginning of the string but there are a short letter with dot (e.g. Ana V.) I was not able to extract the letters.

With the code below,

unique(word(df, 1))
[1] "Alilis" "Ana"    "Anita"

How can I get ?

[1] "Alilis" "Ana T."  "Ana V."  "Anita"
extract string r regex
5 Answers

Try with

gsub("^((\\S+)|^(\\w+ [A-Z]\\.))\\s+.*", "\\1", df)
[1] "Alilis" "Ana T." "Ana V." "Anita"

Should also work if there are multiple spaces

> gsub("^((\\S+)|^(\\w+ [A-Z]\\.))\\s+.*", "\\1", c(df, "Allis hello CELF-4_Data_Entry.xlsx"))
[1] "Alilis" "Ana T." "Ana V." "Anita"  "Allis"
akrun0

Try the following code:

sub("\\s+\\S+$", "", df)

[1] "Alilis" "Ana T." "Ana V." "Anita"
B. Christian Kamgang0

Another option assuming you want everything before ' CELF' like this:

df <- c("Alilis CELF-4_CF_Data_Entry.xlsx" , "Ana T. CELF-4_CF_Data_Entry.xlsx" , "Ana V. CELF-4_CF_Data_Entry.xlsx","Anita CELF-4_CF_Data_Entry.xlsx")

library(stringr)
word(df,1,sep = "\\ CELF")
#> [1] "Alilis" "Ana T." "Ana V." "Anita"

Created on 2022-09-23 with reprex v2.0.2

Quinten0

We can try sub with pattern (\\S+(\\s\\w\\.)?).*, i.e.,

> sub("(\\S+(\\s\\w\\.)?).*", "\\1", df)
[1] "Alilis" "Ana T." "Ana V." "Anita"
ThomasIsCoding0

You can also use extract and positive lokahead:

library(tidyr)
data.frame(df) %>%
  extract(df,
          into = "Name",
          regex = "(.*?)\\sCELF")
    Name
1 Alilis
2 Ana T.
3 Ana V.
4  Anita

The regexpart captures anything that is before ...

  • \\s: one whitespace character followed by ...
  • CELF: ... the literal string CELF
Chris Ruehlemann0
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