将NA移到数据框中每一列的末尾 [英] Move NAs to the end of each column in a data frame

问题描述

我有这样一个数据帧：

df <- structure(list(a = c(NA, NA, 1L, 2L, 3L, 4L, 5L, 6L, 7L, 8L), b = c(NA, NA, NA, 1L, 2L, 3L, 4L, 5L, 6L, 7L), d = c(NA, NA, NA, NA, 1L, 2L, 3L, 4L, 5L, 6L)), .Names = c("a", "b", "d"), row.names = c(NA, -10L), class = "data.frame")

> df
    a  b  d
1  NA NA NA
2  NA NA NA
3   1 NA NA
4   2  1 NA
5   3  2  1
6   4  3  2
7   5  4  3
8   6  5  4
9   7  6  5
10  8  7  6

在每列中，我想将非 NA 的值向上移动，并将 NA 到最后：

In each column, I'd like to move the non-NA values up to the start, and move the NAs to the end:

> df.out
    a  b  d
1   1  1  1
2   2  2  2
3   3  3  3
4   4  4  4
5   5  5  5
6   6  6  6
7   7  7 NA
8   8 NA NA
9  NA NA NA
10 NA NA NA

更新以使我的问题更清楚。

df <- structure(list(a = c(NA, NA, 1, 5, 34, 7, 3, 5, 8, 4), b = c(NA, 
NA, NA, 57, 2, 7, 9, 5, 12, 100), d = c(NA, NA, NA, NA, 5, 7, 
2, 8, 2, 5)), .Names = c("a", "b", "d"), row.names = c(NA, -10L
), class = "data.frame")

> df
    a   b  d
1  NA  NA NA
2  NA  NA NA
3   1  NA NA
4   5  57 NA
5  34   2  5
6   7   7  7
7   3   9  2
8   5   5  8
9   8  12  2
10  4 100  5

应导致：

    a   b  d
1   1  57  5
2   5   2  7
3  34   7  2
4   7   9  8
5   3   5  2
6   5  12  5
7   8 100 NA
8   4  NA NA
9  NA  NA NA
10 NA  NA NA

似乎很简单，但我坚持从哪里开始。您能帮忙吗？

Seems like an easy task but I am stuck on where to start.. Can you help?

推荐答案

在完全误解了问题之后，这是我的最终答案：

After completely misunderstanding the question, here is my final answer:

# named after beetroot for being the first to ever need this functionality
beetroot <- function(x) {
    # count NA
    num.na <- sum(is.na(x))
    # remove NA
    x <- x[!is.na(x)]
    # glue the number of NAs at the end
    x <- c(x, rep(NA, num.na))
    return(x)
}

# apply beetroot over each column in the dataframe
as.data.frame(lapply(df, beetroot))

它将对NA进行计数，删除NA，并在每个列的底部粘贴NA数据框。

It will count the NAs, remove the NAs, and glue NAs at the bottom for each column in the data frame.

这篇关于将NA移到数据框中每一列的末尾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！