使用R将值移到data.frame左侧[复制]

Question

这个问题在这里已有答案：

• How to move cells with a value row-wise to the left in a dataframe [duplicate] 5个答案
• Shifting non-NA cells to the left 4个答案

好的，所以我有这个data.frame：

        A      B      C
1  yellow purple   <NA>
2    <NA>   <NA> yellow
3  orange yellow   <NA>
4  orange   <NA>  brown
5    <NA>  brown purple
6  yellow purple   pink
7  purple  green   pink
8  yellow   pink  green
9  purple orange   <NA>
10 purple   <NA>  brown

我有兴趣从第一列中获取所有缺失的值，并将其替换为其他列中的值，例如行2,4,5和10。

        A      B      C
1  yellow purple   <NA>
2  yellow   <NA>   <NA>
3  orange yellow   <NA>
4  orange  brown   <NA>
5   brown purple   <NA>
6  yellow purple   pink
7  purple  green   pink
8  yellow   pink  green
9  purple orange   <NA>
10 purple  brown   <NA>

我的想法是循环遍历列以获取具有缺失值的行，并将其替换为右侧列中的值，但这也可能存在缺陷，因为如果第2列和第3列中有4列和2个值则为NA。有没有人知道可能有效的算法？

Answer 1

我们可以遍历行并连接非NA元素，然后是NA元素，并将其分配回数据集

df[] <-  t(apply(df, 1, function(x) c(x[!is.na(x)], x[is.na(x)])))
df
#        A      B     C
#1  yellow purple  <NA>
#2  yellow   <NA>  <NA>
#3  orange yellow  <NA>
#4  orange  brown  <NA>
#5   brown purple  <NA>
#6  yellow purple  pink
#7  purple  green  pink
#8  yellow   pink green
#9  purple orange  <NA>
#10 purple  brown  <NA>

data

df <- structure(list(A = c("yellow", NA, "orange", "orange", NA, "yellow", 
"purple", "yellow", "purple", "purple"), B = c("purple", NA, 
"yellow", NA, "brown", "purple", "green", "pink", "orange", NA
 ), C = c(NA, "yellow", NA, "brown", "purple", "pink", "pink", 
 "green", NA, "brown")), .Names = c("A", "B", "C"), row.names = c("1", 
 "2", "3", "4", "5", "6", "7", "8", "9", "10"), class = "data.frame")