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

Answer 2

You just need to use the apply function:

## Example Data
dd = data.frame(col1 = c(0, .3, 0), col2=c(0, 1, 0),
                        col3=c(0.4, 0, 0.8))
apply(dd, 1, function(i) sum(i > 0))

So to add this too your existing data frame:

dd$col4 =  apply(dd, 1, function(i) sum(i > 0))

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Alternatively, we could convert the data frame to logical values then use rowSums

rowSums(dd > 0)