R - 根据同一行不同列的值填充缺失值(空白)

Question

我正在使用 R 并具有以下数据框示例，其中所有变量都是因子:

  first            second  third
 social     birth control   high
            birth control   high
medical  Anorexia Nervosa    low
medical  Anorexia Nervosa    low
               Alcoholism   high
 family        Alcoholism   high

基本上，我需要一个函数来帮助我根据第二列和第三列中的值填充第一列中的空白。例如，如果我在第二列中有“节育”，在第三列中有“高”，我需要用“社会”来填充第一列中的空白。如果第二栏和第三栏分别是“Alcoholism”和“high”，我需要用“family”来填第一栏的空白。

Answer 1

根据显示的数据，对于“second”和“third”的每个组合，“first”中是否有其他值不是很清楚。如果只有一个值，您需要用它替换 ''，那么您可以尝试

library(data.table)
setDT(df1)[, replace(first, first=='', first[first!='']),
                                         list(second, third)]

或者更有效的方法是

setDT(df1)[, first:= first[first!=''] , list(second, third)]
#     first           second third
#1:  social    birth control  high
#2:  social    birth control  high
#3: medical Anorexia Nervosa   low
#4: medical Anorexia Nervosa   low
#5:  family       Alcoholism  high
#6:  family       Alcoholism  high

数据

df1 <- structure(list(first = c("social", "", "medical", "medical", 
"", "family"), second = c("birth control", "birth control", 
"Anorexia Nervosa", 
"Anorexia Nervosa", "Alcoholism", "Alcoholism"), third = c("high", 
"high", "low", "low", "high", "high")), .Names = c("first", "second", 
"third"), class = "data.frame", row.names = c(NA, -6L))