通过删除一些NA单元来压缩数据帧？

If I have a data frame as follows:

如果我有一个数据框如下：

data.frame(
  cola = c(3,NA,NA),
  colb = c(1,NA,NA),
  colc = c(NA,6,NA),
  cold = c(NA,7,NA),
  cole = c(NA,3,NA),
  colf = c(NA,NA,9), 
  colg = c(NA,NA,8)
)

How can I shift all fields to the left, eliminating NA values as needed, as here:

如何将所有字段向左移动，根据需要消除NA值，如下所示：

data.frame(
  cola = c(3,6,9),
  colb = c(1,7,8),
  colc = c(NA,3,NA)
)

Thanks for any help.

谢谢你的帮助。

3 个解决方案

#1

We loop through the rows, remove the NA elements with na.omit and then append NA at the end based on the max length of the list

我们循环遍历行，用na.omit删除NA元素，然后根据列表的最大长度在末尾追加NA

lst <- apply(df1, 1, na.omit)
out <- as.data.frame(do.call(rbind, lapply(lst, `length<-`, max(lengths(lst)))))

#2

Another option could be:

另一种选择可能是：

library(tidyverse)

df %>% rownames_to_column() %>%
    gather(measure, value, -rowname) %>%
    group_by(rowname) %>%
    na.omit() %>%
    mutate(measure = paste0("col", row_number())) %>%
    spread(measure, value) %>%
    ungroup() %>%
    select(-rowname)
#    col1  col2  col3
# 1     3     1    NA
# 2     6     7     3
# 3     9     8    NA

#3

You can transpose, drop NAs, transpose back:

您可以转置，删除NAs，转置回：

library(magrittr)
library(data.table)

DF %>% transpose %>% lapply(na.omit) %>% transpose %>% 
  data.frame %>% setNames(names(DF)[seq_along(.)])

  cola colb colc
1    3    1   NA
2    6    7    3
3    9    8   NA

#1