# NOT RUN {
# An expression which is partially evaluated
gen.list.expr(a_i + 2 * i, i = 1:4)
# Generate an expression with placeholders a_i,
# generate data for a_1, ..., a_4 and finally evaluate it
expr <- gen.vector.expr(a_i + a_(j+1), i = 1:3, j = 1:3, i != j)
data <- gen.data.frame(c(a_1 = a_1, ..., a_4 = a_4), a_ = 1:2)
eval(expr, data)
# }
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