# [R] For applying formula in rows

Berend Hasselman bhh at xs4all.nl
Wed Jul 13 09:44:40 CEST 2011

```Bansal, Vikas wrote:
>
> Dear all,
>
> I have a problem and it is very difficult for me to get a code.
> I am reading a file(attached with this mail) using the code-
>
> and dataframe df is like this-
>
> V1        V2      CaseA CaseC CaseG CaseT new
>  10 135344109     0     0             1     0        12
>  10 135344110     0     1             0     0         12
>  10 135344111     0     0             1     0         12
>  10 135344112     0     0             1     0          12
>  10 135344113     0     0             1     0          12
>  10 135344114     1     0             0     0          12
>  10 135344115     1     0             0     0           12
>  10 135344116     0     0             0     1           12
>  10 135344117     0     1             0     0           12
>  10 135344118     0     0             0     1            12
>
> I want to apply a formula which is  (number/total)*new*2.
> where number is in column caseA,G,C,T and total is sum of these 4
> columns.I will explain with an example.the output of first row should be-
>
> V1        V2      CaseA CaseC CaseG CaseT new
>  10 135344109     0     0             24     0        12
>
> because sum of 3rd,4th,5th and 6th column is 1 for first row.and for case
> A,C and T if we will apply above formula the answer will be zero
> (0/1)*12*2 which is equal to 0 but for Case G-
> (1/1)*12*2 which is equal to 24.
>

Reading the data the same was as Joshua

str(df)
df[, "total"] <- rowSums(df[, 3:6])

and then why not just

df[, 3:6] <- df[, 3:6] / df[, "total"] * df[, "new"] * 2

Berend

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