R 根据元素和前一个值之间的差值过滤矩阵的元素

你的方法很好，问题是当你的条件不满足时，你没有为case_when设置默认值，而case_when的默认值是NA.如果你把代码改为

case_when(
    difference > 40 ~ NA, .default = a
  )

我想这会起作用的.我会更直接一点，像这样:

set.seed(47)
mydataframe <- data.frame(matrix(runif(n=50, min=1, max=100), nrow=5)) 

library(dplyr)

mydataframe
#         X1       X2       X3        X4       X5        X6       X7       X8        X9      X10
# 1 97.71924 69.44983 14.74096 90.295379 18.63639 38.622468 75.13312 44.52890  6.806878 21.08084
# 2 38.01769 39.51712 70.49673 40.649777 56.12284  4.342001 37.52843 24.84979 37.672119 66.51133
# 3 76.38870 47.42565 17.05717  4.063552 52.06370  4.652532 47.30130 97.66172 60.239314 96.34999
# 4 82.42667 54.78766 60.33139  8.064458 14.20961 54.107717 20.16720 48.89779 93.813872 37.83152
# 5 57.78090 92.56431 51.09757 47.363336 69.23906 80.155587 89.79590 68.70130 37.310393 85.85034

mydataframe |>
  mutate(across(everything(), \(x) abs(ifelse(abs(x - lag(x, default = first(x))) > 40, NA, x))))
#         X1       X2       X3        X4       X5        X6       X7       X8        X9      X10
# 1 97.71924 69.44983 14.74096 90.295379 18.63639 38.622468 75.13312 44.52890  6.806878 21.08084
# 2       NA 39.51712       NA        NA 56.12284  4.342001 37.52843 24.84979 37.672119       NA
# 3 76.38870 47.42565       NA  4.063552 52.06370  4.652532 47.30130       NA 60.239314 96.34999
# 4 82.42667 54.78766       NA  8.064458 14.20961        NA 20.16720       NA 93.813872       NA
# 5 57.78090 92.56431 51.09757 47.363336       NA 80.155587       NA 68.70130        NA       NA


## or using case_when in case you have more conditions
mydataframe |>
  mutate(across(everything(), \(x)
    case_when(
      abs(x - lag(x)) > 40 ~ NA, 
      .default = x
    )
))
## same result as above