Multiples rows to one row in R

Question

In R, I have a data frame with several values. I would like to have a data frame that transforms the data frame into a data frame with just one row with all the values. I have a data frame like this:

df <- data.frame(A = c("time", "time", "time"),
                 B = c("place", "place", "place"),
                 C = c(NA, 1, NA),
                 D = c(NA, NA, 2),
                 E = c(3, NA, NA),
                 `F` = c(4,4, NA),
                 G = c(NA, 5, NA))

     A     B  C  D  E  F  G
1 time place NA NA  3  4 NA
2 time place  1 NA NA  4  5
3 time place NA  2 NA NA NA

And I want a dataframe like this:

     A     B C D E F G
1 time place 1 2 3 4 5

I tried using the function reshape like here: Turning one row into multiple rows in r

And tried the function unique but than I lose a lot of data: Selecting unique rows in matrix using R

Answer 1

We can group by 'A', 'B' and select the first non-NA element across other columns

library(dplyr)
df1 %>%
     group_by(A, B) %>%
     summarise(across(everything(), ~ .[order(is.na(.))][1]), .groups = 'drop')

-output

# A tibble: 1 x 8
#  A     B         C     D     E     F     G H    
#  <chr> <chr> <int> <int> <int> <int> <int> <lgl>
#1 time  place     1     2     3     4     5 NA   

---

Or with coalesce

library(purrr)
df1 %>%
    group_by(A, B) %>% 
    summarise(across(everything(), ~ reduce(., coalesce)), .groups = 'drop')

data

df1 <- structure(list(A = c("time", "time", "time"), B = c("place", 
"place", "place"), C = c(NA, 1L, NA), D = c(NA, NA, 2L), E = c(3L, 
NA, NA), F = c(4L, NA, NA), G = c(NA, 5L, NA), H = c(NA, NA, 
NA)), class = "data.frame", row.names = c(NA, -3L))