Get means, sums and possibly other functions for a select number
  of columns using dplyr::select-style column selection.
row_sums(data, ..., na_rm = FALSE, varname = "sum") row_means(data, ..., na_rm = FALSE, varname = "mean") row_min(data, ..., na_rm = FALSE, varname = "min") row_max(data, ..., na_rm = FALSE, varname = "max") row_apply(data, ..., .fun, varname = "var")
| data | A data frame. | 
|---|---|
| ... | The columns to sum, take the mean of, etc. Required. | 
| na_rm | Whether to remove  | 
| varname | The column name of the sums means etc. as a character string. | 
| .fun | The function to apply. | 
A data frame with a new column representing the sums, means or whatever.
Simple wrappers for applying rowwise operations only for selected
  columns within the tidyverse approach to data processing.  The
  row_apply function requires a function that already works on rows.
#> x y z sum #> 1 1 4 7 5 #> 2 2 5 8 7 #> 3 3 6 9 9#> x y z mean #> 1 1 4 7 4 #> 2 2 5 8 5 #> 3 3 6 9 6#> # A tibble: 3 x 3 #> x y max #> <int> <int> <int> #> 1 1 4 4 #> 2 2 5 5 #> 3 3 6 6#> x y z var #> 1 1 4 7 147 #> 2 2 5 8 258 #> 3 3 6 9 369