Combining two or more columns into one

Question

I have four columns:

Year	I	I	I
1951	4	6	7
1952	8	0	3
1953	3	2	9

how do I combine them into two like that?:

Year	I
1951	4
1951	6
1951	7
1952	8
1952	0
1952	3
1953	3
1953	2
1953	9

Answer 1

I am not completely sure what your format is, but probably you want something like this by using pivot_longer to make your table from wide to long:

df <- data.frame(Year = c(1951, 1952, 1953),
                 v1 = c(4,8,3),
                 v2 = c(6,0,2),
                 v3 = c(7,3,9))

library(tidyr)
df %>%
  pivot_longer(!Year, names_to = "variable", values_to = "values")

Output:

# A tibble: 9 × 3
   Year variable values
  <dbl> <chr>     <dbl>
1  1951 v1            4
2  1951 v2            6
3  1951 v3            7
4  1952 v1            8
5  1952 v2            0
6  1952 v3            3
7  1953 v1            3
8  1953 v2            2
9  1953 v3            9