我需要創建變數“peace”，它告訴我在變數之前有多少年的和平conflict==1（意味著沖突開始）。
有人建議我for用一個以 0 開頭的變數（“和平”）做一個-loop，如果加上 1 conflict==0，保存值 ifconflict==1然后把它放回 0。
這是變數“peace”應該是什么樣子的一個簡短示例：
Df <- data.frame(country = c("A", "A", "A", "A", "A", "B","B", "B", "B"),
year = c("1950", "1951", "1952", "1953", "1954", "1950", "1951", "1952", "1953"),
conflict = c(0, 0, 1, 1, 0, 0, 1, 0, 1), peace = c(0, 0, 2, 2, 0, 0, 1, 0, 1))
實作“和平”的最佳方式是什么？代碼會是什么樣子？
謝謝！
uj5u.com熱心網友回復：
有關 R 中的基本回圈，請參閱此鏈接：https : //www.geeksforgeeks.org/loops-in-r-for-while-repeat/
對于您的問題，您希望迭代每個行索引，除了第一個
# these two lines do two very different things. See if you can spot it.
peace <- 1
Df$peace <- 0
for (i in 2:nrow(Df)) {
# compare row i-1 to i
if (Df$country[i] != Df$country[i-1]) {
peace <- 1
next
}
if (Df$conflict[i] == 0 && Df$conflict[i-1] == 1) {
peace <- 1
} else if (Df$conflict[i] == 0) {
peace <- peace 1
} else {
Df$peace[i] <- peace
}
}
uj5u.com熱心網友回復：
我創建了一個名為n輸出的新變數-
library(dplyr)
Df <- Df %>% mutate(grp = data.table::rleid(conflict))
Df %>%
count(country, grp) %>%
group_by(country) %>%
mutate(n = lag(n, default = 0)) %>%
ungroup %>%
left_join(Df, by = c('country', 'grp')) %>%
mutate(n = replace(n, conflict == 0, 0))
# country grp n year conflict peace
# <chr> <int> <dbl> <chr> <dbl> <dbl>
#1 A 1 0 1950 0 0
#2 A 1 0 1951 0 0
#3 A 2 2 1952 1 2
#4 A 2 2 1953 1 2
#5 A 3 0 1954 0 0
#6 B 3 0 1950 0 0
#7 B 4 1 1951 1 1
#8 B 5 0 1952 0 0
#9 B 6 1 1953 1 1
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