creating a function to compare values of a variables via arithmetic operations across levels of another variable

Question

I want help to create a function that does the following operations:

• create a new variable named division
• put in each row r_n of the variable dT$division the result of the division of the value of the corresponding row r_n of dT$result1 by the value of each row of dT$result1 for dt$treat == A
• create a new variable named operation
• for each row of the variable operation execute dT$operation = (2*(dT$division-1))/(2*(dT$division-1)+1)

Where n in r_n is the number of each row in the data frame, and takes values from 1 to N, and N is the total number of observations or rows in the data frame.

#sample data

(note: edited to add the variable id which is vital to create the desired function)

dT = read.table(header = TRUE, text = "
id group treat result1
1 0 A 0.1438 
2 0 A 0.237 
3 0 B 0.2774 
4 0 B 0.2774 
5 0 B 0.2093 
6 0 C 0.1206 
7 0 C 0.1707 
8 0 C 0.0699 
9 0 C 0.1351 
10 1 C 0.1206 
11 1 A 0.1438 
12 1 A 0.237 
13 1 B 0.2774 
14 1 B 0.2774 
15 1 B 0.2093 
16 1 C 0.1206 
17 1 C 0.1707 
18 1 C 0.0699
19 1 C 0.1351 
20 1 C 0.1206")

#head output

(note: this is a random sample of rows from the original data chosen to facilitate the illustration of the concept)

id group treat result1
1 0 A 0.014
2 0 A 0.02
3 0 B 0.20
4 1 A 0.14
5 1 B 0.27

#expected output

(note: for dT$treat.denominator A2 and A3, this example only shows the visual - because I needed to post the expected output as soon as possible; that means that I calculated the actual values of the variables dT$division and dT$operation only for dT$treat.denominator A1)

id group treat result1 treat.numerator treat.denominator division operation
1 0 A 0.01 A1 A1 1.00 0.00
2 0 A 0.02 A2 A1 1.64 0.56
3 0 B 0.20 B3 A1 20.00 0.97
4 1 A 0.14 A4 A1 14.00 0.96
5 1 B 0.27 B5 A1 27.00 0.98
1 0 A 0.01 A1 A2 1.00 0.00
2 0 A 0.02 A2 A2 1.64 0.56
3 0 B 0.20 B3 A2 20.00 0.97
4 1 A 0.14 A4 A2 14.00 0.96
5 1 B 0.27 B5 A2 27.00 0.98
1 0 A 0.01 A1 A3 1.00 0.00
2 0 A 0.02 A2 A3 1.64 0.56
3 0 B 0.20 B3 A3 20.00 0.97
4 1 A 0.14 A4 A3 14.00 0.96
5 1 B 0.27 B5 A3 27.00 0.98

Thank you in advance for any help.

Answer 1

1. create a new variable named division
2. put in each row r_n of the variable dT$division the result of the division of the value of the corresponding row r_n of dT$result1 by the value of each row of dT$result1 for dt$treat == A

Answer to Steps 1 and 2

  division<-dT$result1/dT$result1[dT$treat=="A"]  

  dT<-cbind(dT,division)

3. create a new variable named operation

4. for each row of the variable operation execute dT$operation = (2*(dT$division-1))/(2*(dT$division-1)+1)

Answers to 3 and 4

dT$operation<-(2*(dT$division-1))/(2*(dT$division-1)+1)