Add PositionMaximum and PositionMinimum #956
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ChrisJefferson
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Current coverage is 48.75% (diff: 100%)@@ master #956 diff @@
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Files 424 424
Lines 222125 222167 +42
Methods 3430 3430
Messages 0 0
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- Hits 108344 108315 -29
- Misses 113781 113852 +71
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Looks sensible and fine to me. |
| ## <#GAPDoc Label="PositionMaximum"> | ||
| ## <ManSection> | ||
| ## <Oper Name="PositionMaximum" Arg='list [, func]'/> | ||
| ## <Oper Name="PositionMinimum" Arg='list [, func]'/> |
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It does not invalidate GAPDoc, but since both PositionMaximum and PositionMinimum are functions, it would be more consistent to use Func instead of Oper in <Oper Name="PositionMaximum" Arg='list [, func]'/> (there is even an automated check for such things added in #538).
| if Length(args) = 2 then | ||
| func := args[2]; | ||
| else | ||
| func := x -> x; |
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Maybe use IdFunc here as in the previous function?
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Certainly should use IdFunc here
| bestindex := fail; | ||
| for i in [ 1 .. Length( list ) ] do | ||
| if IsBound( list[i] ) then | ||
| ival := func ( list[ i ] ); |
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Should we be concerned about performance and treat the 1-argument case differently to avoid calling IdFunc on each element of the list?
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IdFunc is very fast. It might speed it up a little, but at the cost of twice as much, almost identical, code.
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Ok, then let's fix GAPDoc elements and use IdFunc in both functions, and merge this...
ChrisJefferson
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Write below the description of changes (for the release notes)
This adds the new methods
PositionMaximumandPositionMinimum, which returns the index of the largest element of a list. It also can be used to find the largest element under some function.I have had this function privately for some time, and often use it myself. For example, finding the largest element of a list
lof groups can be done byl[PositionMaximum(l, Size)], whereas I don't know of any other short way of doing this in GAP (if I've missed a method somewhere, please tell me).