Question

让我说我有一个df

data111 <- structure(list(`1` = c(20.47039, 21.94899, 22.96345, 23.61655, 
24.50835, 25.92349, 26.34687, 27.83433), `2` = structure(c(4L, 
5L, 2L, 5L, 2L, 3L, 1L, 6L), .Label = c("no", "p", "xa", "xae", 
"xei", "xoe"), class = "factor"), `3` = c(20.65273, 22.0617, 
23.06622, 23.68949, 24.57134, 26.01042, 26.44185, 27.93414)), .Names = c("1", 
"2", "3"), class = "data.frame", row.names = c("1", "2", "3", 
"4", "5", "6", "7", "8"))

我如何制作它以便我可以在填充新列的行上使用if else语句，如果满足特定条件，它会取消（i + 1）和（i）行之间的差异？例如：

for (i in 1:nrow(data111)) {

      if (data111$def[i] == data111$def[i+1]) {
            data111$new <- data111$ghi[i+1] - data111$ghi[i]
      }
      else {
            data111$new <- 0
      }
}

这不起作用..新列应该有行1,5,6,7,8 = 0，行2,3,4等于第3列中的差异（iw第2行新column =第3行第2列 - 第2行第2列之间的差异

Answer 1

我不知道你想对最后一个元素做什么，所以我只是保持原样

#set up our i and i+1 vectors for the column def
ithDef<-data111$def[1:(nrow(data111)-1)]
i_plus_1Def<-data111$def[2:(nrow(data111))]

##set up our i and i+1 vectors for the column ghi
ithGhi<-data111$ghi[1:(nrow(data111)-1)]
i_plus_1Ghi<-data111$ghi[2:(nrow(data111))]

#the last element has no i+1, so I keep the last element the same
newNew<-c(ifelse(ithDef==i_plus_1Def, i_plus_1Ghi-ithGhi, 0), df$new[nrow(df)])

在多行上使用if else语句

1 个答案: