The expand.grid function
This is a useful function for generating tables of combinations of factor levels. Suppose we have three variables: height with five levels between 60 and 80 in steps of 5, weight with five levels between 100 and 300 in steps of 50, and two sexes.
expand.grid(height = seq(60, 80, 5), weight = seq(100, 300, 50), sex = c("Male","Female")) height weight sex 1 60 100 Male 2 65 100 Male 3 70 100 Male 4 75 100 Male 5 80 100 Male 6 60 150 Male 7 65 150 Male 8 70 150 Male 9 75 150 Male 10 80 150 Male 11 60 200 Male ... 47 65 300 Female 48 70 300 Female 49 75 300 Female 50 80 300 Female
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