过滤/删除不正确的行（上方和下方） [英] Filter / Delete incorrect rows (plus above and below)

问题描述

我有一个很大的数据集。
我想删除所有不正确的行。另外，我想删除不正确的行之前和之后的一些行。

I have got a large dataset. I want to delete all incorrect rows. Additionally i want to delete some rows before and after the incorrect row.

我发现有帮助。但不幸的是，这对我来说不起作用。
我想我与行名有关，但我无法解决。
因此，我感谢任何有用的建议。

I found something helpful. But unfortunately it does not work out for me. I think i has to do with the "rownames" but i am not able to fix it. So i appreciate any helpful advices.

library(dplyr)

var1 <- 1:20
var2 <- c(1,1,1,1,0,1,0,1,1,1,0,0,1,1,1,1,1,0,1,1)
var3 <- rep(3, 20)

dat <- data.frame (var1, var2, var3)
View(dat)


extract.with.context <- function(x, rows, after = 0, before = 0) {

  match.idx  <- which(rownames(x) %in% rows)
  span       <- seq(from = -before, to = after)
  extend.idx <- c(outer(match.idx, span, `+`))
  extend.idx <- Filter(function(i) i > 0 & i <= nrow(x), extend.idx)
  extend.idx <- sort(unique(extend.idx))

  return(x[extend.idx, , drop = FALSE])
}

extract.with.context(dat, dat$var2==0, after = 1, before = 1)

View(dat)

#expected output
var1 <- c(1,2,3,9,14,15,16,20)
var2 <- c(1,1,1,1,1,1,1,1)
var3 <- rep(3,length(var2))
dat <- data.frame(var1, var2, var3)
View(dat)

推荐答案

我们得到行索引，其中列等于值，并删除索引 indx 的行， indx +之后和 indx-之前。

We get the index of rows where column is equal to value and remove the rows for indexes indx, indx + after and indx - before.

extract.with.context <- function(df, column, value, before, after) {
    indx <- which(df[[column]] == value)
    df[-c(indx, indx + after, indx - before), ]
}

extract.with.context(dat, "var2", 0, 1, 1)

#   var1 var2 var3
#1     1    1    3
#2     2    1    3
#3     3    1    3
#9     9    1    3
#14   14    1    3
#15   15    1    3
#16   16    1    3
#20   20    1    3

这篇关于过滤/删除不正确的行（上方和下方）的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！