R: combine rows with measurement below certain threshold

Question

I have a "toy" data frame with 2 columns ( x and y ) and 8 rows. I would like to merge and sum all rows where y < 10 . Value of merged x is not very important.

x = c("A","B","C","D","E","F","G","H")
y = c(20,17,16,14,12,9,6,5)

df = data.frame(x,y)
df

    x   y
1   A   20
2   B   17
3   C   16
4   D   14
5   E   12
6   F   9
7   G   6
8   H   5

Desired output:

    x   y
1   A   20
2   B   17
3   C   16
4   D   14
5   E   12
6   F   20

F is not necessary and can be set to Other . Thanks in advance!

Answer 1

I think this is what you are looking for.

x = c("A","B","C","D","E","F","G","H")
y = c(20,17,16,14,12,9,6,5)

df = data.frame(x = x[which(y > 10)],y = y[which(y > 10)])
df = rbind(df,data.frame(x = 'f',y = sum(y[which(y < 10)])))

Answer 2

We can also try with subset/transform/rbind

 rbind(subset( df, y>=10), 
      transform(subset(df, y<10), x= x[1], y= sum(y))[1,])