有条件地用NA替换色谱柱 [英] Conditionally replace columns with NA

问题描述

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

I want to replace all numbers in columns time1 and time2 with NA after the row where there is a 1 in m$swim. It should look like this:

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

Thank you!

推荐答案

在 dplyr 中，您可以执行以下操作:

In dplyr you can do :

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.

A base R option however, would be more efficient.

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

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