Averaging noncontiguous numbers ignoring zeros?

I'm trying to calculate an average but I want to not include any values of
zero. I've seen examples here and in Microsft help for contiguous values (ex:
A1:A7) but not for the averages of noncontiguous data (ex: A1, A3, A5).

I found Microsoft's example using contiguous data under "Calculate the
average of numbers, ignoring zero (0) values". They show how to average
A1:A6 using:
=AVERAGE(IF(A2:A7<0, A2:A7,"")) . I've not been able to revise this
formula to calculate noncontiguous data. Any ideas?
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Cheers,
Mike