# [PYTHON MATRIX-SIG] Pseudo Indices

**Chris Chase S1A
**
chris.chase@jhuapl.edu

*Tue, 30 Jan 1996 17:53:56 -0500*

>>* a[RubberIndex, 3].
*
Guido> You could sneak this into the abovementioned patch as "a[::, 3]".
Actually, All is equivalent to "::" and it corresponds to the nil
index syntax of Yorick (which is indicated by whitespace between the
commas) and the * index syntax of Matlab or IDL.
Rubber indexes are different. Yorick has two types of rubber indexes,
one has syntax "*" and the other is ".." and neither type has the same
behavior as "::". Both types act as if the entire length of the
missing intervening dimensions were selected. "*" collapses the
missing intervening dimensions into 1 dimension. ".." does not
collapse the intervening dimensions (it is like using All for the
missing dimensions).
Currently the Numeric module RubberIndex is like the Yorick ".."
rubber index. I imagine that the collapsing type rubber index could
easily be added by applying a shape change to the current RubberIndex
behavior. What would be a possible name for this type of rubber
index? CollapseIndex?
Chris
=================
MATRIX-SIG - SIG on Matrix Math for Python
send messages to: matrix-sig@python.org
administrivia to: matrix-sig-request@python.org
=================