Question

这是我的数据示例：

m <- data.frame(swim = c(0,1,0,0), time1 = c(1,2,3,4), time2 = c(2,3,4,5))

我想在NA中有1的行之后，用m$swim替换time1和time2列中的所有数字。它应该看起来像这样：

n <- data.frame(swim = c(0,1,0,0), time1 = c(1,2,NA,NA), time2 = c(2,3,NA,NA))

Thank you!

Answer 1

在dplyr中，您可以执行以下操作：

library(dplyr)
m %>%
  mutate(across(starts_with('time'), 
           ~replace(., row_number() > match(1, swim), NA)))

但是，基本的R选项会更有效。

cols <- grep('time', names(m))
inds <- match(1, m$swim)
m[(inds + 1):nrow(m), cols] <- NA
m
#  swim time1 time2
#1    0     1     2
#2    1     2     3
#3    0    NA    NA
#4    0    NA    NA

Answer 2

base R解决方案是：

#Data
m <- data.frame(swim = c(0,1,0,0), time1 = c(1,2,3,4), time2 = c(2,3,4,5))
#Detect position
index <- min(which(m$swim==1)) 
#Replace
m[(index+1):dim(m)[1],-1] <- NA

输出：

  swim time1 time2
1    0     1     2
2    1     2     3
3    0    NA    NA
4    0    NA    NA

Answer 3

使用data.table，结果如下：

library(data.table)
setDT(m)

#Start after the row with the 1
stop.here <- which(m$swim == 1)+1

these_rows <- seq(stop.here,length(m$swim),1)

m <- m[these_rows,time1:=NA]
m <- m[these_rows,time2:=NA]

有条件地用NA替换色谱柱

3 个答案: