I want to compute a new variable (newvar) based on the values of two other
variables (t1freq, t2freq).The two variables (t1freq,t2freq) are contained
in a dataframe - study1dat <-
read.csv("c:\\study1rb.csv",header=T) .
I gather this computation can be done using Apply and I have run the
following example from the help menu
## Compute row and column sums for a matrix:
x <- cbind(x1 = 3, x2 = c(4:1, 2:5))
dimnames(x)[[1]] <- letters[1:8]
apply(x, 2, mean, trim = .2)
col.sums <- apply(x, 2, sum)
row.sums <- apply(x, 1, sum)
rbind(cbind(x, Rtot = row.sums), Ctot = c(col.sums, sum(col.sums)))
My questions are:
1. I don't understand what values I would need to enter for my 2 variables
(data is included at end of this message) in the 'cbind' command
2. For the second row, what modification is required?
3. If I wanted to compute a mean, I believe the 'mean' is substituted
for
sum - if so, in the case where there is only one value, is it possible to
obtain this as the mean rather than obtaining an NA?
4. How do I save 'newvar' into the original datafile?
Any assistance with this enquiry is appreciated,
Bob
id t1freq t2freq
1 4 6
2 3 3
3 7 5
4 0 2
5 1 4
6 7 7
7 7 7
8 7 4
9 7 7
10 5 4
11 3 6
12 1 3
13 7 7
14 7 7
15 1 3
16 7 7
17 2 1
18 7 7
19 7 6
20 3 4
21 7 7
22 7 6
23 3 0
24 7 6
25 7 6
26 5 6
27 7 7
28 7 7
29 5 7
30 7 2
31 5 6
32 5 7
33 7 7
34 7 7
35 7 7
36 7 7
37 6 5
38 4 4
39 4 6
40 7 7
41 3 3
42 4 4
43 7 7
44 7 7
45 7 1
46 2 2
47 4 2
48 1 1
49 4 4
50 0 0
51 7 7
52 7 2
53 4 7
54 0 NA
55 5 4
56 0 0
57 5 5
58 5 6
59 7 7
60 5 4
61 1 4
62 6 7
63 4 5
64 6 7
65 5 4
66 1 0
67 7 7
68 5 3
69 7 7
70 4 7
71 3 7
72 7 7
73 4 2
74 4 6
75 7 5
76 0 0
77 7 6
78 3 3
79 7 7
80 2 4
81 4 1
82 1 4
83 4 2
84 2 1
85 5 0
86 1 3
87 0 0
88 7 7
89 3 1
90 6 6
91 2 1
92 4 3
