Question

我正在清理从Excel导入的一些数据。我试图根据数据框中行的位置创建一列值。具体来说，我尝试使用mutate()和ifelse()为具有特定字符值的两行之间的行分配值。以下是我正在使用的数据的一个非常简化的示例：

a b [1,] "5" "yes" [2,] "6" "no" [3,] "7" "no" [4,] "2" "yes" [5,] "apple" NA [6,] "4" "yes" [7,] "1" "no" [8,] "banana" NA [9,] "6" "yes" [10,] "3" "yes"

我想创建一个c列，返回颜色的字符值，其中"apple"和"banana"之间的行（行号[6]和[7]）被指定c列值为"red"，所有其他行的值均为"blue"。有没有办法做到这一点？如果我能更清楚地解释我的问题，请告诉我！

Answer 1

使用row_number包

中的dplyr功能

#reproducing example
df <- data.frame(a = c("5","6","7","2","apple","4","1","banana","6","3"), b = c("yes","no","no","yes","NA","yes","no","NA","yes","yes"), stringsAsFactors = FALSE)

df$c <- "blue"
lim1 <- which(df$a == "apple")
lim2 <- which(df$a == "banana")

方法1：

df$c[lim1:lim2] <- "red"

方法2：

library(dplyr)
df <- df %>%
    mutate(c = ifelse(row_number(a) %in% lim1:lim2, "blue", "red"))

Answer 2

我们可以通过编程方式获取职位，然后进行分配

i1 <- Reduce(`:`, which(is.na(df1$b))+ c(1, -1))
df1$c <- 'blue'
df1$c[i1] <- 'red'

数据

df1 <- structure(list(a = c("5", "6", "7", "2", "apple", "4", "1", "banana", 
"6", "3"), b = c("yes", "no", "no", "yes", NA, "yes", "no", NA, 
"yes", "yes")), .Names = c("a", "b"), class = "data.frame", row.names = c(NA, 
-10L))

Answer 3

首先，您的数据看起来像是矩阵而不是data.frame，如果您计划使用dplyr，则应该修复它。排序后，您可以在每个字词上使用cumsum（如果您不想计算apple行，则会滞后），减去，然后使用ifelse转换{ {1}}和0到1和blue：

red

Answer 4

dplyr包提供row_number()函数，可与mutate和ifelse结合使用，为特定行位置指定值：

library(dplyr)
df = df %>% mutate(c=ifelse(row_number(a) %in% c(6,7),"red","blue"))

Answer 5

使用mutate和dplyr：

df %>% mutate(c = ifelse(row_number() %>% between(match("apple",a)+0.1,match("banana",a)-0.1),"red","blue"))

with base：

df <- transform(df,c = ifelse(1:nrow(df) > match("apple",a) & (1:nrow(df) < match("banana",a) ),"red","blue"))

根据相对行位置改变值

5 个答案:

数据