library(tidyverse)
DF %>%
  pivot_longer(everything()) %>%
  count(value, name) %>%
  pivot_wider(names_from = name, values_from = n, values_fill = 0)

# A tibble: 6 × 5
  value column1 column2 column3 column4
  <dbl>   <int>   <int>   <int>   <int>
1  0          4       3       2       1
2  0.3        0       0       2       3
3  0.4        1       1       1       1
4  0.5        1       1       2       0
5  0.75       0       1       0       0
6  1          2       2       1       3

如果你想玩一点for循环，试试这个：

unicos <- unique(unlist(DF))
DF_count <- 0*DF[1:length(unicos),]

for(i in 1:ncol(DF_count)){
  for(j in 1:length(unicos)){
    DF_count[j,i] <- sum(DF[,i]  %in% unicos[j])
  }
}

DF_count <- data.frame(column_unique =  unicos, DF_count)
DF_count <- DF_count[order(DF_count$column_unique), ]
DF_count

  column_unique column1 column2 column3 column4
1          0.00       4       3       2       1
6          0.30       0       0       2       3
4          0.40       1       1       1       1
2          0.50       1       1       2       0
5          0.75       0       1       0       0
3          1.00       2       2       1       3