Convert column classes in data.table

by

For a single column:

dtnew <- dt[, Quarter:=as.character(Quarter)]
str(dtnew)

Classes ‘data.table’ and 'data.frame':  10 obs. of  3 variables:
 $ ID     : Factor w/ 2 levels "A","B": 1 1 1 1 1 2 2 2 2 2
 $ Quarter: chr  "1" "2" "3" "4" ...
 $ value  : num  -0.838 0.146 -1.059 -1.197 0.282 ...

Using lapply and as.character:

dtnew <- dt[, lapply(.SD, as.character), by=ID]
str(dtnew)

Classes ‘data.table’ and 'data.frame':  10 obs. of  3 variables:
 $ ID     : Factor w/ 2 levels "A","B": 1 1 1 1 1 2 2 2 2 2
 $ Quarter: chr  "1" "2" "3" "4" ...
 $ value  : chr  "1.487145280568" "-0.827845218358881" "0.028977182770002" "1.35392750102305" ...

More Related Contents:

  1. Select / assign to data.table when variable names are stored in a character vector
  2. Is there a dplyr equivalent to data.table::rleid?
  3. Assign multiple columns using := in data.table, by group
  4. Efficient way to rbind data.frames with different columns
  5. How to replace NA values in a table for selected columns
  6. data.table “key indices” or “group counter”
  7. Select subset of columns in data.table R [duplicate]
  8. How to extract the first n rows per group?
  9. Finding Overlaps between interval sets / Efficient Overlap Joins
  10. Force character vector encoding from “unknown” to “UTF-8” in R
  11. Operator == inconsistent in logical columns in data.table
  12. Rolling join on data.table with duplicate keys
  13. Why is using update on a lm inside a grouped data.table losing its model data?
  14. Complex non-equi merge in R
  15. ‘Embedded nul in string’ error when importing csv with fread
  16. eval and quote in data.table
  17. Efficiently computing a linear combination of data.table columns
  18. R fuzzy string match to return specific column based on matched string
  19. When should I use the := operator in data.table?
  20. Subsetting data.table by 2nd column only of a 2 column key, using binary search not vector scan
  21. Using dynamic column names in `data.table`
  22. Conditional binary join and update by reference using the data.table package
  23. How do you delete a column by name in data.table?
  24. How does one change the levels of a factor column in a data.table
  25. When should I use setDT() instead of data.table() to create a data.table?
  26. DT[!(x == .)] and DT[x != .] treat NA in x inconsistently
  27. In R data.table, how do I pass variable parameters to an expression?
  28. Merging two sets of data by data.table roll=’nearest’ function
  29. assigning by reference into loaded package datasets
  30. calculating sum of previous 3 rows in R data.table (by grid-square)

Leave a Comment