我试图根据网格方形ID为R中的数据框中的观察值分配区域。我有以下数据框( df ):
for(i in 1:length(df$square)) {
for(j in 1:length(N)) {
if(df$square[i]==N[j]){
df$area[i]=="N"}
}
}
for(i in 1:length(df$square)) {
if(any(df$square==N)==T){
df$area[i]=="North"}
}
我想为"区域"添加另一个列,将每个观察分配到" North"," East"," South& #34;或" West"基于网格方块。我已经尝试了以下 for 循环,但没有做任何事情,
N <- c("A1","A2","B2")
其中&#34; N&#34;是我创建的一个对象,包含位于北方的方块,即:
{{1}}
我确实找到了以下相关问题,但我想知道在涉及角色时它是否有所不同:Assign a group number based on another column by group in R
任何帮助将不胜感激。感谢
答案 0 :(得分:1)
我建议使用第二个N
配对方块而不是像data.frame
那样定义向量:
df <- data.frame(year = 2000,
month = c(2,2,2,2,2,3,3,3),
square = c("A1", "B2", "H5", "J9", "A2", "N8", "M9", "C7"),
stringsAsFactors = FALSE)
areas <- data.frame(square = c("A1", "A2", "B1", "H5", "J9", "M9", "N8"),
area = c("N", "N", "N", "W", "E", "S", "S"),
stringsAsFactors = FALSE)
有了它,只需进行合并:
merge(df, areas, by = "square", all.x = TRUE)
# square year month area
# 1 A1 2000 2 N
# 2 A2 2000 2 N
# 3 B2 2000 2 <NA>
# 4 C7 2000 3 <NA>
# 5 H5 2000 2 W
# 6 J9 2000 2 E
# 7 M9 2000 3 S
# 8 N8 2000 3 S
(NA
是因为areas
定义不完整。)
答案 1 :(得分:0)
d <- data.frame(year = rep(2000, 8), month = rep(3,8),
square = c("A1", "B2", "H5", "J9", "A2", "N8", "M9", "C7"))
N <- c("A1","A2","B2")
for(i in 1:nrow(d)) {
if (d$square[i] %in% N) {
d$area[i] <- "North"
}
else (
d$area[i] <- "Somewhere Else"
)
}
用于其他基数方向id向量的for循环中的else if()语句中的图层
答案 2 :(得分:0)
在R中,通常最好避免循环,尤其是嵌套循环。对于这种情况,我更喜欢sapply()
。
N <- c("A1","A2","B2")
#assume these are the other designations
S <- c("H5", "J9")
E <- c("N8","M9")
W <- c("C7")
mydat$area<- sapply(mydat$square, function (x){
if (x %in% N) return("North")
if (x %in% S) return("South")
if (x %in% E) return("East")
if (x %in% W) return("West")
else NA
})
mydat
year month square area
2000 2 A1 North
2000 2 B2 North
2000 2 H5 South
2000 2 J9 South
2000 2 A2 North
2000 3 N8 East
2000 3 M9 East
2000 3 C7 West
当你开始拥有大型数据集时,*apply()
函数将比R中的循环快得多。