当我想要创建ifelse或新if...else变量时，我仍然会使用vector和data.frame绊倒。这个问题的标题似乎密切相关，但没有解决我的问题：Why can't R's ifelse statements return vectors?
以下代码显示了我创建变量my.data2$v1b和my.data2$v2b的尝试。我在ifelse和if...else失败了，然后成功了for-loop和apply。
有没有办法用my.data2$v1b或my.data2$v2b创建ifelse和if...else？我假设不是基于我的尝试和其他Stack Overflow个问题。那么，在R中创建这些变量的规范方法是什么？使用apply有效，但看起来相当复杂。使用for-loop有效但我得到的印象是for-loops。
关于ifelse有很多问题，但我找不到解决这个问题的问题：鉴于ifelse和if...else似乎不起作用，最佳解决方案是什么？ ？对不起，如果这是重复的。
这是我的数据集：
my.data2 <- read.table(text = '
refno v1 v2 state1 state2 xday first last
111 41 47 1 2 42 1 2
111 41 47 1 2 42 2 1
222 45 49 1 4 47 1 2
222 45 49 1 4 47 2 1
333 59 65 1 2 65 1 2
333 59 65 1 2 65 2 1
444 45 49 1 2 48 1 2
444 45 49 1 2 48 2 1
555 66 80 1 2 75 1 2
555 66 80 1 2 75 2 1
666 103 109 1 2 108 1 2
666 103 109 1 2 108 2 1
777 43 46 1 2 45 1 2
777 43 46 1 2 45 2 1
', header = TRUE, stringsAsFactors = FALSE)
以下是所需的载体：
desired.data.v1b <- c(41,42, 45,47, 59,65, 45,48, 66,75, 103,108, 43,45)
desired.data.v2b <- c(42,47, 47,49, 65,65, 48,49, 75,80, 108,109, 45,46)
这是我开始尝试创建这些向量的地方：
v1b <- my.data2$v1
v2b <- my.data2$v2
# this ifelse does not work
my.data2$v1b < ifelse(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$last == 1, my.data2$xday, my.data2$v1)
my.data2$v2b < ifelse(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$first == 1, my.data2$xday, my.data2$v2)
# this if...else does not work
if(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$last == 1) {v1b = my.data2$xday} else {v1b = my.data2$v1}
if(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$first == 1) {v2b = my.data2$xday} else {v2b = my.data2$v2}
# this for-loop works
for(i in 1:nrow(my.data2)) {
if(my.data2$state1[i] == 1 & my.data2$state2[i] %in% c(2,4) & my.data2$last[i] == 1) {v1b[i] = my.data2$xday[i]}
if(my.data2$state1[i] == 1 & my.data2$state2[i] %in% c(2,4) & !(my.data2$last[i] == 1)) {v1b[i] = my.data2$v1[i] }
if(my.data2$state1[i] == 1 & my.data2$state2[i] %in% c(2,4) & my.data2$first[i] == 1) {v2b[i] = my.data2$xday[i]}
if(my.data2$state1[i] == 1 & my.data2$state2[i] %in% c(2,4) & !(my.data2$first[i] == 1)) {v2b[i] = my.data2$v2[i] }
}
all.equal(desired.data.v1b, v1b)
all.equal(desired.data.v2b, v2b)
my.data2$v1b <- v1b
my.data2$v2b <- v2b
# this apply works
my.v1 <- apply(my.data2, 1, function(x) {if (x['state1'] == 1 & x['state2'] %in% c(2,4) & x['last'] == 1) {x['v1b'] = x['xday']} else {x['v1b'] = x['v1']}})
my.v2 <- apply(my.data2, 1, function(x) {if (x['state1'] == 1 & x['state2'] %in% c(2,4) & x['first'] == 1) {x['v2b'] = x['xday']} else {x['v2b'] = x['v2']}})
names(my.v1) <- NULL
names(my.v2) <- NULL
all.equal(desired.data.v1b, my.v1)
all.equal(desired.data.v2b, my.v2)
修改
也许这是规范的解决方案？
my.data2$v1b <- rep(-99, nrow(my.data2))
my.data2$v2b <- rep(-99, nrow(my.data2))
my.data2$v1b[(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$last == 1) ] <- my.data2$xday[(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$last == 1) ]
my.data2$v1b[(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & !(my.data2$last == 1))] <- my.data2$v1[ (my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & !(my.data2$last == 1))]
my.data2$v2b[(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$first == 1) ] <- my.data2$xday[(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & my.data2$first == 1) ]
my.data2$v2b[(my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & !(my.data2$first == 1))] <- my.data2$v2[ (my.data2$state1 == 1 & my.data2$state2 %in% c(2,4) & !(my.data2$first == 1))]
all.equal(desired.data.v1b, my.data2$v1b)
all.equal(desired.data.v2b, my.data2$v2b)