Might the DeleteCases have issues in matching when the list is of floats (machine precision numbers)? E.g. in this code it might fail to match correctly because float==float is not a good operation:

a = RandomReal[{0, 1}, 5]
DeleteCases[a, Max[a]]

How would you handle this type of situations? What is the robust way?

  • 5
    $\begingroup$ In the posted example it will not fail because Max[a] is a member of a so it must match. $\endgroup$ – Rohit Namjoshi Mar 29 '20 at 22:49
  • $\begingroup$ But might there be rounding issues somewhere in the Max that would cause the matching to fail? $\endgroup$ – Al Guy Mar 29 '20 at 23:12
  • $\begingroup$ No issues in this example. But if there were, the robust method is to allow some appropriate epsilon plus/minus. $\endgroup$ – Daniel Lichtblau Mar 30 '20 at 14:28

A slightly faster method (30x for large lists) is to use Ordering and Drop:

Drop[a, Ordering[a, -1]]

This will always remove 1 element, even in the extreme rare case that the maximum value appears twice…


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