dtplyr (version 1.3.1)

fill.dtplyr_step: Fill in missing values with previous or next value

Description

This is a method for the tidyr fill() generic. It is translated to data.table::nafill(). Note that data.table::nafill() currently only works for integer and double columns.

Usage

# S3 method for dtplyr_step
fill(data, ..., .direction = c("down", "up", "downup", "updown"))

Arguments

data

A data frame.

...

<tidy-select> Columns to fill.

.direction

Direction in which to fill missing values. Currently either "down" (the default), "up", "downup" (i.e. first down and then up) or "updown" (first up and then down).

Examples

library(tidyr)

# Value (year) is recorded only when it changes
sales <- lazy_dt(tibble::tribble(
  ~quarter, ~year, ~sales,
  "Q1",    2000,    66013,
  "Q2",      NA,    69182,
  "Q3",      NA,    53175,
  "Q4",      NA,    21001,
  "Q1",    2001,    46036,
  "Q2",      NA,    58842,
  "Q3",      NA,    44568,
  "Q4",      NA,    50197,
  "Q1",    2002,    39113,
  "Q2",      NA,    41668,
  "Q3",      NA,    30144,
  "Q4",      NA,    52897,
  "Q1",    2004,    32129,
  "Q2",      NA,    67686,
  "Q3",      NA,    31768,
  "Q4",      NA,    49094
))

# `fill()` defaults to replacing missing data from top to bottom
sales %>% fill(year)

# Value (n_squirrels) is missing above and below within a group
squirrels <- lazy_dt(tibble::tribble(
  ~group,    ~name,     ~role,     ~n_squirrels,
  1,      "Sam",    "Observer",   NA,
  1,     "Mara", "Scorekeeper",    8,
  1,    "Jesse",    "Observer",   NA,
  1,      "Tom",    "Observer",   NA,
  2,     "Mike",    "Observer",   NA,
  2,  "Rachael",    "Observer",   NA,
  2,  "Sydekea", "Scorekeeper",   14,
  2, "Gabriela",    "Observer",   NA,
  3,  "Derrick",    "Observer",   NA,
  3,     "Kara", "Scorekeeper",    9,
  3,    "Emily",    "Observer",   NA,
  3, "Danielle",    "Observer",   NA
))

# The values are inconsistently missing by position within the group
# Use .direction = "downup" to fill missing values in both directions
squirrels %>%
  dplyr::group_by(group) %>%
  fill(n_squirrels, .direction = "downup") %>%
  dplyr::ungroup()

# Using `.direction = "updown"` accomplishes the same goal in this example