Create new dummy variable columns from categorical variable

by

R has a “sub-language” to translate formulas into design matrix, and in the spirit of the language you can take advantage of it. It’s fast and concise. Example: you have a cardinal predictor x, a categorical predictor catVar, and a response y.

> binom <- data.frame(y=runif(1e5), x=runif(1e5), catVar=as.factor(sample(0:4,1e5,TRUE)))
> head(binom)
          y          x catVar
1 0.5051653 0.34888390      2
2 0.4868774 0.85005067      2
3 0.3324482 0.58467798      2
4 0.2966733 0.05510749      3
5 0.5695851 0.96237936      1
6 0.8358417 0.06367418      2

You just do

> A <- model.matrix(y ~ x + catVar,binom) 
> head(A)
  (Intercept)          x catVar1 catVar2 catVar3 catVar4
1           1 0.34888390       0       1       0       0
2           1 0.85005067       0       1       0       0
3           1 0.58467798       0       1       0       0
4           1 0.05510749       0       0       1       0
5           1 0.96237936       1       0       0       0
6           1 0.06367418       0       1       0       0

Done.

More Related Contents:

  1. Pass a data.frame column name to a function
  2. Plot two graphs in same plot in R
  3. Gradient of n colors ranging from color 1 and color 2
  4. The condition has length > 1 and only the first element will be used
  5. How to sort letters in a string?
  6. floating point issue in R? [duplicate]
  7. ggplot2: facet_wrap strip color based on variable in data set
  8. R list of lists to data.frame
  9. Is it possible to use spread on multiple columns in tidyr similar to dcast? [duplicate]
  10. Sum all values in every column of a data.frame in R
  11. Euclidean distance of two vectors
  12. How to extract the fill colours from a ggplot object?
  13. How to merge and sum two data frames
  14. find neighbouring elements of a matrix in R
  15. Create categorical variable in R based on range
  16. dplyr mutate rowwise max of range of columns
  17. Using dynamic column names in `data.table`
  18. Splitting a data frame into equal parts
  19. How to draw a nice arrow in ggplot2
  20. Deploying R shiny app as a standalone application [closed]
  21. Spreading a two column data frame with tidyr
  22. Getting a function name as a string
  23. How to calculate number of days between two dates in R
  24. How to convert dd/mm/yy to yyyy-mm-dd in R
  25. Reusing a Model Built in R
  26. Undefined columns selected when subsetting data frame
  27. Generate all possible permutations (or n-tuples)
  28. devtools::install_github() – Ignore SSL cert verification failure
  29. fast large matrix multiplication in R
  30. When does the argument go inside or outside aes()?

Leave a Comment