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Text replacement - "</code>" to "</source>"
Miraheze>Adám Brudzewsky m (Text replacement - "<code>" to "<source lang=apl inline>") |
Miraheze>Adám Brudzewsky m (Text replacement - "</code>" to "</source>") |
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The arguments to Drop must be valid arguments to [[Take]], and elements of the left argument are matched to [[axes]] of the right in the same way. Like Take, the left argument is subject to [[scalar rank extension]], and in some APLs the right is as well. | The arguments to Drop must be valid arguments to [[Take]], and elements of the left argument are matched to [[axes]] of the right in the same way. Like Take, the left argument is subject to [[scalar rank extension]], and in some APLs the right is as well. | ||
Each axis with a matching left argument element <source lang=apl inline>d</ | Each axis with a matching left argument element <source lang=apl inline>d</source> is modified to remove <source lang=apl inline>|d</source> indices, or all of them if <source lang=apl inline>|d</source> is larger than the length of the axis. Indices are removed starting from the beginning if <source lang=apl inline>d</source> is positive and starting from the end if it is negative (if <source lang=apl inline>d</source> is 0, then no indices are removed). Equivalently, for an axis of length <source lang=apl inline>l</source>, <source lang=apl inline>l-l⌊|d</source> axes are retained—not dropped—from the axis starting from the opposite side: the end if <source lang=apl inline>d</source> is positive and the beginning otherwise. If <source lang=apl inline>|d</source> is greater than or equal to <source lang=apl inline>l</source> for any axis, then the result is [[empty array|empty]] and shares a [[prototype]] with the argument. | ||
=== APL Model === | === APL Model === | ||
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} | } | ||
</source> | </source> | ||
The code works by modifying the left argument using the right argument's shape. First, the shape is used to restrict the left argument's range (<source lang=apl inline>(-s)⌈s⌊⍺</ | The code works by modifying the left argument using the right argument's shape. First, the shape is used to restrict the left argument's range (<source lang=apl inline>(-s)⌈s⌊⍺</source>) so that the maximum number of indices dropped is the length of the axis. Then, the shape is added or subtracted so that the left argument's sign is flipped. | ||
This implementation inherits all argument extensions from Take. The two middle lines are used to support right argument scalar rank extension and the [[SHARP APL]] short left argument extension. If Take does not have these extensions then they have no effect and can be removed. | This implementation inherits all argument extensions from Take. The two middle lines are used to support right argument scalar rank extension and the [[SHARP APL]] short left argument extension. If Take does not have these extensions then they have no effect and can be removed. | ||
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* [http://microapl.com/apl_help/ch_020_020_570.htm APLX] | * [http://microapl.com/apl_help/ch_020_020_570.htm APLX] | ||
* [https://www.jsoftware.com/help/dictionary/d531.htm J Dictionary], [https://code.jsoftware.com/wiki/Vocabulary/curlyrtdot#dyadic J NuVoc] (as <source lang=apl inline>}.</ | * [https://www.jsoftware.com/help/dictionary/d531.htm J Dictionary], [https://code.jsoftware.com/wiki/Vocabulary/curlyrtdot#dyadic J NuVoc] (as <source lang=apl inline>}.</source>) | ||
{{APL built-ins}} | {{APL built-ins}} | ||