Question

我正在寻找一种从另一数据帧填充数据帧的快速方法。为此，我想使用dplyr包。例如，请考虑以下代码，它替换了dt2中dt1中的NA。我的目标是避免循环for。

set.seed(123)
  dt1 <- data.frame(ID = c(104, 109, 111, 121), a = c(1, 8, 5, 9), b = c(100, 220, 877, 120), c = c(1, 3, 2, 3))
  ## print(dt1)
  dt2 <- data.frame(ID = c(rep(104, 1), rep(109, 3), rep(111, 2), rep(121, 3)), 
                    a = c(rep(NA, 1), rep(NA, 3), rep(NA, 2), rep(NA, 3)),
                    b = c(rep(NA, 1), rep(NA, 3), rep(NA, 2), rep(NA, 3)))
  ## print(dt2)

  for(i in as.vector(dt1[,c("ID")])) {

    dt2[dt2[, c("ID")] %in% i, c("a")] <- sample(0:dt1[dt1[, c("ID")] == i, c("a")], size = dt1[dt1[, c("ID")] == i, c("c")], replace = T)
    dt2[dt2[, c("ID")] %in% i, c("b")] <- sample(0:dt1[dt1[, c("ID")] == i, c("b")], size = dt1[dt1[, c("ID")] == i, c("c")], replace = T)

  }
  print(dt2)

输出为：

>   print(dt2)
   ID a   b
1 104 0  79
2 109 3  10
3 109 7 116
4 109 8 197
5 111 3 840
6 111 2 398
7 121 6 108
8 121 5  29
9 121 1   5

这是我第一次使用dplyr软件包进行测试：

  set.seed(123)
  dt1 <- data.frame(ID = c(104, 109, 111, 121), a = c(1, 8, 5, 9), b = c(100, 220, 877, 120), c = c(1, 3, 2, 3))
  ## print(dt1)
  dt2 <- data.frame(ID = c(rep(104, 1), rep(109, 3), rep(111, 2), rep(121, 3)), 
                    a = c(rep(NA, 1), rep(NA, 3), rep(NA, 2), rep(NA, 3)),
                    b = c(rep(NA, 1), rep(NA, 3), rep(NA, 2), rep(NA, 3)))
  i <- 104
  test <- dt2 %>%
    mutate(a = replace(a, ID == i, sample(0:dt1[dt1[, c("ID")] == i, c("a")], size = dt1[dt1[, c("ID")] == i, c("c")], replace = T)),
           b = replace(b, ID == i, sample(0:dt1[dt1[, c("ID")] == i, c("b")], size = dt1[dt1[, c("ID")] == i, c("c")], replace = T)))
  print(test)

但是，我不知道如何考虑ID，i.e., with i = 104, i = 109, i = 111, and i = 121

上的循环

Answer 1

我们可以使用left_join，其中'dt1'由'ID'，然后按'ID'，transmute，“ a”和“ b”列进行分组

left_join(dt2[1], dt1, by = "ID") %>%
    group_by(ID) %>% 
    transmute(a = sample(0:a[1], size = c[1], replace = TRUE),
              b = sample(0:b[1], size = c[1], replace = TRUE))

它也可以通过'df1'

完成

dt1 %>%
    rowwise() %>%
    mutate_at(vars(a, b), funs(list(sample(0:., size = c, replace = TRUE)))) %>%
    unnest %>%
    select(-c)

如何使用“ dplyr”从另一个数据帧重现“ for”循环以填充数据帧？

1 个答案: