嵌套ifasser語句我仍在學習如何將SAS代碼轉換為R，并收到警告。我需要弄清楚我在哪里犯錯誤。我想要做的是創建一個變量來總結和區分一個人口的三個狀態：大陸，海外，外國人。我有一個包含兩個變量的數據庫：ID國籍：idnat(法語、外國人)、如果idnat那么法語是：身份證出生地：idbp(內地、殖民地、海外)我想總結一下idnat和idbp到一個名為idnat2:地位：K(內地、海外、外國人)所有這些變量都使用“字符類型”。第2欄預期的結果： idnat idbp idnat21 french mainland mainland2 french colony overseas3 french overseas overseas4 foreign
foreign foreign下面是我想在R中翻譯的SAS代碼：if idnat = "french" then do;
if idbp in ("overseas","colony") then idnat2 = "overseas";
else idnat2 = "mainland";end;else idnat2 = "foreigner";run;以下是我在R中的嘗試：if(idnat=="french"){
idnat2 <- "mainland"} else if(idbp=="overseas"|idbp=="colony"){
idnat2 <- "overseas"} else {
idnat2 <- "foreigner"}我收到這樣的警告：Warning message:In if (idnat=="french") { :
the condition has length > 1 and only the first element will be used我被建議使用“嵌套”ifelse“相反，它的輕松，但得到更多的警告：idnat2 <- ifelse (idnat=="french", "mainland",
ifelse (idbp=="overseas"|idbp=="colony", "overseas")
)
else (idnat2 <- "foreigner")根據警告消息，長度大于1，因此只考慮第一個括號之間的內容。對不起，我不明白這個長度和這里有什么關系？有人知道我哪里錯了嗎？
3 回答
胡說叔叔
TA貢獻1804條經驗 獲得超8個贊
# some sample dataidnat <- sample(c("french","foreigner"),100,TRUE)idbp <- rep(NA,100)idbp[idnat=="french"]
<- sample(c("mainland","overseas","colony"),sum(idnat=="french"),TRUE)# recodingout <- ifelse(idnat=="french" &
!idbp %in% c("overseas","colony"), "mainland",
ifelse(idbp %in% c("overseas","colony"),"overseas",
"foreigner"))cbind(idnat,idbp,out) # check resultifelseif("french"=="french")if(c("french","foreigner")=="french")
ifelseifelseifelse
慕運維8079593
TA貢獻1876條經驗 獲得超5個贊
如果數據集包含許多行，則使用data.table而不是嵌套ifelse().
提供了下面的查找表
lookup
idnat idbp idnat2
1: french mainland mainland
2: french colony overseas
3: french overseas overseas
4: foreign foreign foreign
和一個樣本數據集
library(data.table)
n_row <- 10L
set.seed(1L)
DT <- data.table(idnat = "french",
idbp = sample(c("mainland", "colony", "overseas", "foreign"), n_row, replace = TRUE))
DT[idbp == "foreign", idnat := "foreign"][]
idnat idbp
1: french colony
2: french colony
3: french overseas
4: foreign foreign
5: french mainland
6: foreign foreign
7: foreign foreign
8: french overseas
9: french overseas
10: french mainland
然后我們可以做一個加入時更新:
DT[lookup, on = .(idnat, idbp), idnat2 := i.idnat2][]
idnat idbp idnat2
1: french colony overseas
2: french colony overseas
3: french overseas overseas
4: foreign foreign foreign
5: french mainland mainland
6: foreign foreign foreign
7: foreign foreign foreign
8: french overseas overseas
9: french overseas overseas
10: french mainland mainland
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