I am trying to create a data-frame of the column type and unique variables for each column.
I am able to get column type in the desired data-frame format using map(df, class) %>% bind_rows() %>% gather(key = col_name, value = col_class), but unable to get the unique variables to become a data-frame instead of a list.
Below is a small data-frame and code that gets the unique variables in a list, but not a data frame. Ideally, I could do this in one (map) function, but if I have to join them, it would not be a big deal.
df <- data.frame(v1 = c(1,2,3,2), v2 = c("a","a","b","b"))
library(tidyverse)
map(df, class) %>% bind_rows() %>% gather(key = col_name, value = col_class)
map(df, unique)
When I try to use the same method on the map(df, unique) as on the map(df, class) I get the following error: Error: Argument 2 must be length 3, not 2 which is expected, but I am not sure how to get around it.
The number of unique values are different in those two columns. You need to reduce them to a single element.
df2 <- map(df, ~str_c(unique(.x),collapse = ",")) %>%
bind_rows() %>%
gather(key = col_name, value = col_unique)
> df2
# A tibble: 2 x 2
col_name col_class
<chr> <chr>
1 v1 1,2,3
2 v2 a,b