tidyfst (version 0.8.8)

set_dt: Fast operations of data.table by reference

Description

Combination of set* functions provided by data.table. This is memeroy efficient because no copy is made at all.

Usage

set_dt(
  data,
  col_order = NULL,
  order_by = NULL,
  order_dirc = 1L,
  old_name = NULL,
  new_name = NULL,
  fill_cols = NULL,
  fill_type = "down",
  fill_value = NA
)
mutate_ref(data, ..., by)

Arguments

data

A data.frame

col_order

(Optional) Character vector of the new column name ordering. May also be column numbers. This parameter will pass to "neworder" parameter in setcolorder.

order_by

(Optional) A character vector of column names by which to order. This parameter will pass to "cols" parameter in setorder.

order_dirc

(Optional) An integer vector with only possible values of 1 and -1, corresponding to ascending and descending order. This parameter will pass to "order" parameter in setorder. Default uses 1.

old_name

(Optional) When new_name is provided, character names or numeric positions of column names to change. This parameter will pass to "old" parameter in setnames.

new_name

(Optional) It can be a function or the new column names. This parameter will pass to "new" parameter in setnames.

fill_cols

(Optional) Numeric or character vector specifying columns to be updated.

fill_type

(Optional) Character, one of "down", "up" or "replace". Defaults to "down".

fill_value

(Optional) Numeric or integer, value to be used to fill when fill_type=="replace". Defaults to NA.

...

List of variables or name-value pairs of modifications functions.

by

Mutate by which group(s)?

Value

The input is modified by reference, and returned (invisibly) so it can be used in compound statements.

Details

The set_dt() will first set any data.frame to a data.table, then rename, fill NAs, arrange row order, arrange column order. If you want to do the operation in another order, use it separately in multiple set_dt functions in the desired order.

The mutate_ref() will first set any data.frame to a data.table, then mutate values by reference.

See Also

setcolorder, setorder, setnames, setnafill

Examples

# NOT RUN {
# set_dt
x = 1:10
x[c(1:2, 5:6, 9:10)] = NA
dt = data.table(v1=x, v2=lag_dt(x)/2, v3=lead_dt(x, 1L)/2)
dt
set_dt(dt,new_name = c("A","B","C"),fill_cols = names(dt),
        order_by = "A",order_dirc = -1,col_order = c("B","A","C"))
dt

 # mutate_ref
 copy(iris) -> a
 # never use pipe(%>%) for the `mutate_ref` function
 mutate_ref(a,one = 1,two = 2)
 a
# }