Togaware DATA MINING
Desktop Survival Guide
by Graham Williams
Google

Simple Linking

The merge function can be used to join several datasets on common fields. the default behaviour is to join on any columns that the data frames have in common. This is what we demonstrate below.



> ds1 <- read.table(file("clipboard"), header=T)
> ds1
  id age gender
1  1  32      M
2  2  45      F
3  3  29      F
> ds2 <- read.table(file("clipboard"), header=T)
> ds2
  id day   x1
1  1   1 0.52
2  1   2 0.72
3  1   3 0.29
4  2   1 0.51
5  2   2 0.18
6  3   2 0.22
7  3   3 0.54
> ds3 <- read.table(file("clipboard"), header=T)
> ds3
  id day   x2
1  1   1 0.34
2  1   2 0.55
3  1   3 0.79
4  2   1 0.12
5  2   2 0.23
6  3   2 0.45
7  3   3 0.56
> merge(ds1, ds2)
  id age gender day   x1
1  1  32      M   1 0.52
2  1  32      M   2 0.72
3  1  32      M   3 0.29
4  2  45      F   1 0.51
5  2  45      F   2 0.18
6  3  29      F   2 0.22
7  3  29      F   3 0.54
> merge(merge(ds1, ds2), ds3)
  id day age gender   x1   x2
1  1   1  32      M 0.52 0.34
2  1   2  32      M 0.72 0.55
3  1   3  32      M 0.29 0.79
4  2   1  45      F 0.51 0.12
5  2   2  45      F 0.18 0.23
6  3   2  29      F 0.22 0.45
7  3   3  29      F 0.54 0.56



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