rowwise_mutate {tidyft}

Computation by rows

Description

Compute on a data frame a row-at-a-time. This is most useful when a vectorised function doesn't exist. Only mutate and summarise are supported so far.

Usage

rowwise_mutate(.data, ...)

rowwise_summarise(.data, ...)

Arguments

.data

A data.table

...

Name-value pairs of expressions

Value

A data.table

See Also

rowwise

Examples

# without rowwise
df <- data.table(x = 1:2, y = 3:4, z = 4:5)
df %>% mutate(m = mean(c(x, y, z)))
# with rowwise
df <- data.table(x = 1:2, y = 3:4, z = 4:5)
df %>% rowwise_mutate(m = mean(c(x, y, z)))


# # rowwise is also useful when doing simulations
params = fread(" sim n mean sd
  1  1     1   1
  2  2     2   4
  3  3    -1   2")

params %>%
  rowwise_summarise(sim,z = rnorm(n,mean,sd))