扩展值以填充缺少的值

dplyr tidyr replace

library(dplyr)
library(tidyr)

dat2 <- dat %>%
  group_by(user) %>%
  fill(action) %>%
  ungroup() %>%
  replace(., is.na(.), 0)
dat2
# # A tibble: 10 x 2
#     user action
#    <int>  <dbl>
#  1     1      0
#  2     1      2
#  3     1      2
#  4     1      2
#  5     1      3
#  6     1      3
#  7     2      0
#  8     2      0
#  9     2      1
# 10     2      1

dat <- read.table(text = "user   action
    1       NA
                  1        2
                  1       NA
                  1       NA 
                  1        3
                  1       NA
                  2       NA
                  2       NA
                  2        1
                  2       NA",
                  header = TRUE, stringsAsFactors = FALSE)

ave na.locf0 na.fill

library(zoo)

transform(DF, action = na.fill(ave(action, user, FUN = na.locf0), 0))

   user action
1     1      0
2     1      2
3     1      2
4     1      2
5     1      3
6     1      3
7     2      0
8     2      0
9     2      1
10    2      1

DF <- structure(list(user = c(1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L
), action = c(NA, 2L, NA, NA, 3L, NA, NA, NA, 1L, NA)), 
class = "data.frame", row.names = c(NA, -10L))

ifelse cummax ave

ave(ifelse(!is.na(dat$action), dat$action, 0), dat$user, FUN=cummax)
[1] 0 2 2 2 3 3 0 0 1 1