[英]ordered grouping of rows in R
我想創建一個新列,按順序標記行組。 原始數據:
> dt = data.table(index=(1:10), group = c("apple","apple","orange","orange","orange","orange","apple","apple","orange","apple"))
> dt
index group
1: 1 apple
2: 2 apple
3: 3 orange
4: 4 orange
5: 5 orange
6: 6 orange
7: 7 apple
8: 8 apple
9: 9 orange
10: 10 apple
期望的輸出:
index group id
1: 1 apple 1
2: 2 apple 1
3: 3 orange 1
4: 4 orange 1
5: 5 orange 1
6: 6 orange 1
7: 7 apple 2
8: 8 apple 2
9: 9 orange 2
10: 10 apple 3
dplyr
嘗試:
dt %>% group_by(group) %>% mutate( id= row_number())
# A tibble: 10 x 3
# Groups: group [2]
index group id
<int> <chr> <int>
1 1 apple 1
2 2 apple 2
3 3 orange 1
4 4 orange 2
5 5 orange 3
6 6 orange 4
7 7 apple 3
8 8 apple 4
9 9 orange 5
10 10 apple 5
如何編輯這個以使第一組蘋果為1,然后第一組橙子為1,然后第二組蘋果為2等(參見上面的所需輸出)。 也對data.table
解決方案開放。
library(data.table)
dt[, id := cumsum(c(TRUE, diff(index) > 1)), by="group"]
dt
# index group id
# 1: 1 apple 1
# 2: 2 apple 1
# 3: 3 orange 1
# 4: 4 orange 1
# 5: 5 orange 1
# 6: 6 orange 1
# 7: 7 apple 2
# 8: 8 apple 2
# 9: 9 orange 2
# 10: 10 apple 3
從原來的dt
開始:
library(dplyr)
dt %>%
group_by(group) %>%
mutate(id = cumsum(c(TRUE, diff(index) > 1))) %>%
ungroup()
# # A tibble: 10 x 3
# index group id
# <int> <chr> <int>
# 1 1 apple 1
# 2 2 apple 1
# 3 3 orange 1
# 4 4 orange 1
# 5 5 orange 1
# 6 6 orange 1
# 7 7 apple 2
# 8 8 apple 2
# 9 9 orange 2
# 10 10 apple 3
基地R,也許有點笨重:
out <- do.call(rbind, by(dt, dt$group,
function(x) transform(x, id = cumsum(c(TRUE, diff(index) > 1)))))
out[order(out$index),]
# index group id
# apple.1 1 apple 1
# apple.2 2 apple 1
# orange.3 3 orange 1
# orange.4 4 orange 1
# orange.5 5 orange 1
# orange.6 6 orange 1
# apple.7 7 apple 2
# apple.8 8 apple 2
# orange.9 9 orange 2
# apple.10 10 apple 3
使用rownames(out) <- NULL
可以輕松刪除名稱。 order
部分不是必需的,但我希望以與其他解決方案相同的順序呈現它,而do.call
/ by
不保留原始訂單。
使用data.table::rleid
兩次的另一個選項:
dt[, gid := rleid(group)][, id := rleid(gid), .(group)]
我們也可以使用base R
rle
with(dt, with(rle(group), rep(ave(seq_along(values),
values, FUN = seq_along), lengths)))
#[1] 1 1 1 1 1 1 2 2 2 3
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