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.
A data frame.
<tidy-select> Columns to fill.
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).
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)
#> Source: local data table [16 x 3]
#> Call: copy(`_DT10`)[, `:=`(year = nafill(year, "locf"))]
#>
#> quarter year sales
#> <chr> <dbl> <dbl>
#> 1 Q1 2000 66013
#> 2 Q2 2000 69182
#> 3 Q3 2000 53175
#> 4 Q4 2000 21001
#> 5 Q1 2001 46036
#> 6 Q2 2001 58842
#> # ℹ 10 more rows
#>
#> # Use as.data.table()/as.data.frame()/as_tibble() to access results
# 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()
#> Source: local data table [12 x 4]
#> Call: copy(`_DT12`)[, `:=`(n_squirrels = nafill(nafill(n_squirrels,
#> "locf"), "nocb")), by = .(group)]
#>
#> group name role n_squirrels
#> <dbl> <chr> <chr> <dbl>
#> 1 1 Sam Observer 8
#> 2 1 Mara Scorekeeper 8
#> 3 1 Jesse Observer 8
#> 4 1 Tom Observer 8
#> 5 2 Mike Observer 14
#> 6 2 Rachael Observer 14
#> # ℹ 6 more rows
#>
#> # Use as.data.table()/as.data.frame()/as_tibble() to access results
# Using `.direction = "updown"` accomplishes the same goal in this example