Question

var1 var2 var3
   1    2    3
   1    2    3
   1    2    3

I want to stack var2 and var3 underneath var1 to get:

var1
   1
   1
   1
   2
   2
   2
   3
   3
   3

I tried:

data$var <- append(data$var1,data$var2)

Then I get an error that my replacement has more rows. How do I solve this?

Answer 1

df <- data.frame(var1=1:3,var2=4:6,var3=7:9)
df2 <- stack(df)
print(df2)

  values  ind
1      1 var1
2      2 var1
3      3 var1
4      4 var2
5      5 var2
6      6 var2
7      7 var3
8      8 var3
9      9 var3