mjhjmtu

I am trying to define a substitution that gives 1 for odd numbers and 0 for even numbers. My guess was (in a particular example)

0, 1, 2, 3, 4, 5, 6 /. N_Integer -> If[EvenQ[N], 0, 1]

But the output is 1,1,1,1,1,1,1. The problem is in EvenQ which is acting on a symbol, but I specified before that it should be applied only to integers, so I do not understand why it does not work.

Where is the problem? Does it have something to do with ->?

See JM's comment. The following points in a somewhat more general direction for some queries.

Boole@EvenQ@Range[0, 6]

In case speed matters Mod suggested by J.M. in comments is orders of magnitude faster than ReplaceAll and Boole:

SeedRandom[1]
input = RandomInteger[10^6, 10^6];
First[RepeatedTiming[res0 = input /. n_Integer :> If[EvenQ[n], 1, 0];]]

0.836

First[RepeatedTiming[ res1 = Boole@EvenQ@input; ]]

.021

First[RepeatedTiming[res2 = With[True = 1, False = 0, Evaluate@EvenQ[input]]; ]]

0.047

First[RepeatedTiming[ res3 = 1 - Mod[input, 2];]] 

0.0084

res0 == res1 == res2 == res3
> True

where the trick in res2 is from this answer by Mr.Wizard.