How to move elements of a column up to top of dataframe in R

August 19, 2022

So, I have a dataframe that looks something like this:

A    B    C

a1   NA   NA

a2   NA   NA

NA   b1   NA

NA   NA   c1

NA   NA   c2

I want to make it look like this:

A    B    C

a1   b1   c1

a2   NA   c2

In other words, right now the dataframe is perfectly diagonal. I want to end up with 3 orderly columns and it doesn’t matter to me if there are NAs after the last element in each column. How can I do this in R? Tidyverse solution would be best but not exclusively looking for one.

>Solution :

We could loop across the columns, order based on the NA elements and then filter only rows having at least one non-NA

library(dplyr)
df1 %>%
  mutate(across(everything(), ~ .x[order(is.na(.x))])) %>%
  filter(if_any(everything(), complete.cases))

-output

   A    B  C
1 a1   b1 c1
2 a2 <NA> c2

Or using base R

df1[] <- lapply(df1, \(x)  x[order(is.na(x))])
df1[rowSums(!is.na(df1)) > 0,]
   A    B  C
1 a1   b1 c1
2 a2 <NA> c2

data

df1 <- structure(list(A = c("a1", "a2", NA, NA, NA), B = c(NA, NA, "b1", 
NA, NA), C = c(NA, NA, NA, "c1", "c2")), class = "data.frame", 
row.names = c(NA, 
-5L))