Calculate row specific based on min

Question

My data looks like this

df <- data.frame(x = c(3, 5, 4, 4, 3, 2),
                 y = c(.9, .8, 1, 1.2, .5, .1))

I am trying to multiply each x value by either y or 1, depending on which has the least value.

df$z <- df$x * min(df$y, 1)

The problem is it is taking the min of the whole column, so it is multiplying every x by 0.1.

Instead, I need x multiplied by .9, .8, 1, 1, .5, .1...

Answer 1

We need pmin that will go through each value of 'y' and get the minimum val when it is compared with the second value (which is recycled)

pmin(df$y, 1)
#[1] 0.9 0.8 1.0 1.0 0.5 0.1

Likewise, we can have n arguments (as the parameter is ...)

pmin(df$y, 1, 0)
#[1] 0 0 0 0 0 0

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To get the output, just multiply 'x' with the pmin output

df$x * pmin(df$y, 1)

which can also be written as

with(df, x * pmin(y, 1))