Number of column values greater than 0 for given row? [duplicate]

Answer 1

Another option is Reduce with + after looping over the columns to create a list of logical vectors

dd$col4 <- Reduce(`+`, lapply(dd, `>`, 0))
dd
#  col1 col2 col3 col4
#1  0.0    0  0.4    1
#2  0.3    1  0.0    2
#3  0.0    0  0.8    1