Question

Let’s say I have the following data frame:

> df = data.frame(seq(0, 150, length.out=11), 1:11, rep(0, 11), sample(1:50, 11), 
+ sample(1:50, 11), sample(1:50, 11))
> colnames(df) = c("Time", "Inc", "Side", "Pat1", "Pat2", "Pat3")
> df
    Time Inc Side Pat1 Pat2 Pat3
1     0   1    0   48   49   13
2    15   2    0   43   33   15
3    30   3    0   27   48   38
4    45   4    0   41   47   46
5    60   5    0   11   25   37
6    75   6    0    5   15    4
7    90   7    0   17   22    2
8   105   8    0   10   41   24
9   120   9    0   45   21   33
10  135  10    0   19   26   41
11  150  11    0   25   42   45

Now I want to repeat the first 3 columns n times (n = number of Pat columns) and attach it one below each other. Then I want to place Pat2 below Pat1, Pat3 below Pat2, …

My first intetion was to split the df into a Time/Inc/Side part and a Pat part, but I had problems arranging the columns below each other. Any suggestions?

Answer 1

An alternative approach using reshape2 and melt

# recreate the data 
df = data.frame(seq(0, 150, length.out=11), 1:11, rep(0, 11), sample(1:50, 11), 
 sample(1:50, 11), sample(1:50, 11))
colnames(df) = c("Time", "Inc", "Side", "Pat1", "Pat2", "Pat3")
library(reshape2)

melt(df, id.vars = c('Time', 'Inc', 'Side'))

   Time Inc Side variable value
1     0   1    0     Pat1     7
2    15   2    0     Pat1    18
3    30   3    0     Pat1    10
4    45   4    0     Pat1    35
5    60   5    0     Pat1    30
6    75   6    0     Pat1    32
7    90   7    0     Pat1    12
8   105   8    0     Pat1    38
9   120   9    0     Pat1    26
.......