On Dec 12, 4:24 pm, Jason Grout <jason-s...@creativetrax.com> wrote: > [f(x) for x in [1..10] if f(x)>0]
This is actually bad style. It means that f gets evaluated twice for all the values that end up in the list. The magma language solves this with modified semantics for the "where" clause. One would write: [ v : x in [1..10] | v gt 0 where v:=f(x)] The point being that for every iteration of x, the where clause supplies a variable local to the condition which survives into the value computing part. Does python have a similar construct? I guess a nested construction with iterators might come close: [v for v in ( f(x) for x in [1..10] ) if v > 0] but I don't know what the overhead is in that construction. -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
