Remove part of a string

Question

How do I remove part of a string   For example in ATGAS 1121 I want to remove everything before

User · Answer

Maybe the most intuitive solution is probably to use the stringr function str_remove which is even easier than str_replace as it has only 1 argument instead of 2.

The only tricky part in your example is that you want to keep the underscore but its possible: You must match the regular expression until it finds the specified string pattern (?=pattern).

See example:

strings = c("TGAS_1121", "MGAS_1432", "ATGAS_1121")
strings %>% stringr::str_remove(".+?(?=_)")

[1] "_1121" "_1432" "_1121"

User · Answer

Use regular expressions   In this case  you can use gsub   gsub              ATGAS 1121    1    1121    This regular expression matches the beginning of the string      any character     repeated zero or more times      and underscore       The   makes the match  lazy  so that it only matches are far as the first underscore   That match is replaced with just an underscore   See  regex for more details and references

User · Answer

If you re a Tidyverse kind of person  here s the stringr solution   R gt  library stringr  R gt  strings   c  TGAS 1121    MGAS 1432    ATGAS 1121    R gt  strings   gt   str replace              1    1121    1432    1121    Or  R gt  strings   gt   str replace    A-Z          1    1121    1432    1121

User · Answer

Here s the strsplit solution if s is a vector    gt  s  lt - c  TGAS 1121    MGAS 1432    gt  s1  lt - sapply strsplit s  split      fixed TRUE   function x   x 2     gt  s1  1   1121   1432

User · Answer

You can use a built-in for this  strsplit    gt  s    TGAS 1121   gt  s1   unlist strsplit s  split      fixed TRUE   2   gt  s1       1   1121    strsplit returns both pieces of the string parsed on the split parameter as a list  That s probably not what you want  so wrap the call in unlist  then index that array so that only the second of the two elements in the vector are returned   Finally  the fixed parameter should be set to TRUE to indicate that the split parameter is not a regular expression  but a literal matching character

User · Answer

Here the strsplit solution for a dataframe using dplyr package  col1   c  TGAS 1121    MGAS 1432    ATGAS 1121    col2   c  T    M    A    df   data frame col1  col2  df         col1 col2 1  TGAS 1121    T 2  MGAS 1432    M 3 ATGAS 1121    A  df lt -mutate df col1 as character col1   df2 lt -mutate df col1 sapply strsplit df col1  split      fixed TRUE  function x   x 2     df2    col1 col2 1 1121    T 2 1432    M 3 1121    A

[r] Remove part of a string

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