Get the min of two columns

Question

I want to get the minimum of two columns and create a column in the same data.frame. How can I do that?

For example:

ID    Parm1   Parm2  1      1       2  2      0       1  3      2       1  4      1       0  5      2       0 

Desired output :

ID    Parm1    Parm2     Min  1      1        2        1  2      0        1        0  3      2        1        1  4      1        0        0  5      2        0        0 

Answer 1

You want the parallel minimum implemented in function pmin(). For example using your data:

dat <- read.table(text = "ID    Parm1   Parm2  1      1       2  2      0       1  3      2       1  4      1       0  5      2       0", header = TRUE) 

you can use transform() to add the min column as the output of pmin(Parm1, Parm2) and access the elements of dat without indexing:

dat <- transform(dat, min = pmin(Parm1, Parm2)) 

This gives:

> dat   ID Parm1 Parm2 min 1  1     1     2   1 2  2     0     1   0 3  3     2     1   1 4  4     1     0   0 5  5     2     0   0