Hi,
I need to perform calculations on subsets of a data frame:
DF = data.frame(read.table(textConnection(" A B C D E F
1 a 1995 0 4 1
2 a 1997 1 1 3
3 b 1995 3 7 0
4 b 1996 1 2 3
5 b 1997 1 2 3
6 b 1998 6 0 0
7 b 1999 3 7 0
8 c 1997 1 2 3
9 c 1998 1 2 3
10 c 1999 6 0 0
11 d 1999 3 7 0
12 e 1995 1 2 3
13 e 1998 1 2 3
14 e 1999 6 0 0"),head=TRUE,stringsAsFactors=FALSE))
I'd like to create new dataframes for each unique year in which for each
value of A, the values of D, E and F are summed over the last 3 years (e.g.
1998 = 1998, 1997, 1996):
Question 1: How do I go from DF to newDFyear?
Examples:
newDF1995
B D E F
a 0 4 1
b 3 7 0
e 1 2 3
newDF1998
B D E F
a 1 1 3
b 8 4 6
c 2 4 6
e 1 2 3
Then, for each new DF I need to generate a square matrix after doing the
following:
newDF1998$G<-newDF1998$D + newDF1998$E + newDF1998$F
newDF1998$D<-newDF1998$D/newDF1998$G
newDF1998$E<-newDF1998$E/newDF1998$G
newDF1998$F<-newDF1998$F/newDF1998$G
newDF1998<-NewDF1998[,c(-5)]
newDF1998
B D E F
a 0.2 0.2 0.6
b 0.4 0.2 0.3
c 0.2 0.3 0.5
e 0.2 0.3 0.5
Question 2: How do I go from newDF1998 to a matrix
a b c e
a
b
c
e
in which Cell ab = (0.2*0.4 + 0.2*0.2 + 0.6*0.3)/((0.2*0.2 + 0.2*0.2 +
0.6*0.6)^0.5) * ((0.4*0.4 + 0.2*0.2 + 0.3*0.3)^0.5) = 0.84
Thanks a lot for your help!
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