r: Manipulate data so that columns with same values combine in particular ways - r

Question

I have a dataframe where each column is made up of zero along with one other number. For example:
I want to manipulate the dataframe so that columns that contain the same other number become one column where the value stays as the other number if the other number was present in every row, otherwise it turns to zero.
So for instance, I would want the dataframe above to look like
..1 ..2 ..3
1 2 3
0 2 0
0 0 0
1 0 0
The first row of the dataframe is 1 because the values were both 1 in the first row of the original. The second row of the first column is 0 because there were a 1 and a 0 in the row.
Here is some reproducible data:
structure(list(...1 = c(1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), ...2 = c(1, 0,
0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0, 0,
0, 0, 0, 0, 0), ...3 = c(2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
2, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), ...4 = c(3,
0, 0, 3, 0, 0, 0, 0, 3, 0, 0, 3, 0, 0, 0, 0, 3, 0, 0, 3, 0, 0,
0, 0, 0, 0, 0, 0), ...5 = c(3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0), ...6 = c(3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0,
0, 3, 3, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)), row.names = c(NA,
-28L), class = "data.frame")

Answer 1

Here is a possible solution in base R, where dat is the data frame you provide in the question. We find the unique value for each column, assuming there is only one nonzero value in each column. Then we loop through the groups of columns with each unique value, applying the function all() to each row of the subsetted dataframe to identify rows with all nonzero values. Multiply the resulting logical vector by the value itself to get the desired result. Then store this vector in a list and bind to a data frame.
col_vals <- apply(dat, 2, max)
columns <- list()
for (val in unique(col_vals)) {
columns[[length(columns) + 1]] <- val * apply(dat[, col_vals == val, drop = FALSE], 1, all)
}
as.data.frame(do.call(cbind, columns))