Split text string in a data.table columns

by

Update: From version 1.9.6 (on CRAN as of Sep’15), we can use the function tstrsplit() to get the results directly (and in a much more efficient manner):

require(data.table) ## v1.9.6+
dt[, c("PX", "PY") := tstrsplit(PREFIX, "_", fixed=TRUE)]
#    PREFIX VALUE PX PY
# 1:    A_B     1  A  B
# 2:    A_C     2  A  C
# 3:    A_D     3  A  D
# 4:    B_A     4  B  A
# 5:    B_C     5  B  C
# 6:    B_D     6  B  D

tstrsplit() basically is a wrapper for transpose(strsplit()), where transpose() function, also recently implemented, transposes a list. Please see ?tstrsplit() and ?transpose() for examples.

See history for old answers.

More Related Contents:

  1. data.table vs dplyr: can one do something well the other can’t or does poorly?
  2. Why does data.table update names(DT) by reference, even if I assign to another variable?
  3. How to delete a row by reference in data.table?
  4. Why does X[Y] join of data.tables not allow a full outer join, or a left join?
  5. How to get week numbers from dates?
  6. dplyr mutate/replace several columns on a subset of rows
  7. Proper/fastest way to reshape a data.table
  8. Data.table meta-programming
  9. Evaluating both column name and the target value within `j` expression within `data.table`
  10. Fill in missing values by group in data.table
  11. dplyr on data.table, am I really using data.table?
  12. data.table and parallel computing
  13. Elegantly assigning multiple columns in data.table with lapply()
  14. Sort a data.table fast by Ascending/Descending order
  15. Join R data.tables where key values are not exactly equal–combine rows with closest times
  16. how to show a legend on dual y-axis ggplot
  17. Rolling Sum by Another Variable in R
  18. Why is as.Date slow on a character vector?
  19. Use of lapply .SD in data.table R
  20. How to group data.table by multiple columns?
  21. Apply a function to a subset of data.table columns, by column-indices instead of name
  22. Selecting a subset of columns in a data.table
  23. Merge overlapping ranges into unique groups, in dataframe
  24. add missing rows to a data table
  25. Convert a data frame to a data.table without copy
  26. Row sums over columns with a certain pattern in their name
  27. paste two data.table columns
  28. Removing multiple columns from R data.table with parameter for columns to remove
  29. Merging multiple data.tables
  30. Fill option for fread

Leave a Comment