[Pytables-users] Indexing Arrays: a la numarray

[travlr <vel...@gm...>]

Hi all,

In a previous thread, I discussed with Fransesc about being able to
incorporate non-sequential indexing arrays (key arrays) in the
following ways:

select and get (or set values) tables.Table.Table <rows>=20
select and get (or set values) tables.Table.Column <items>
select and get (or set values) tables.Array <items>

via: object[key] =3D value(s)

I was able to use the patch Fransesc had provided, and also (with my
extremely limited expertise) a little more including using Numeric
arrays and Python lists for the keys (all getting/setting intended
except enabling the tables.Array[key] functionality). Unfortunately, I
at some point accidently erased the damn file :-(

Today, I went back and got the "selecting and getting" Table <rows> and
Column <elements> for versions 1.0 and 1.1 working again, The attachments
provided are a tables.Table.dif file for each version.
Below is an example of it's usage.

I was not able to do any more especially for the newer versions. I am
hoping for this functionality, as well as being able to set the values
via... keys of a non-sequential index_array:

tables.Table[index_array] =3D value(s); and
tables.Column[index_array] =3D value(s); and
tables.Array[index_array] =3D value(s)

Also Fransesc, two questions:
1) Could the tables.Table.Column also have an .nrows (nelements) attribute?
2) Once bounded, tables.Table used to return as a <class
'numarray.records.RecArray'> object. Now it returns a <class
'tables.nestedrecords.NestedRecArray'> object....Is this necessary?.

Thank You
############# EXAMPLE ###########
import tables as ta
import numarray as na

# test_file is one of my actual files (renamed)
hfile =3D ta.openFile('~/data/h5/test_folder/test_file.h5','a')

# These are pointers to tables.Table=20
# objects (not bounded or returned)
mtable =3D hfile.root.d_050808.d_050808
mcolumn =3D mtable.cols.A1

# mtable is a tables.Table.Table of a=20
# particular day in my database.
print
print 'type(mtable)........ ',type(mtable)
print 'mtable.nrows....... ',mtable.nrows
print 'type(mcolumn).... ',type(mcolumn)

# NOTE to Francesc: Why no nrows (nelements) for columns?
####        print 'mcolumn.nrows... ',mcolumn.nrows

# This will return an non-sequential index=20
# smaller than the table's (or column's)=20
#     original index
index =3D na.where(mcolumn[:]=3D=3D2)[0]
print
print 'index.size....... ', index.size()

# The non-sequential index is applied
# To the tables.Table and and tables.Table.Column
# and returns a numarray.records object (or an array object=20
#    for the column) with the specified indexing
rtable =3D mtable[index]
rcolumn =3D mcolumn[index]

print
print 'type(rtable)..... ',type(rtable)
print 'rtable.size()..... ',rtable.size()
print 'rcolumn.size()..',rcolumn.size()

hfile.close()

############# RESULT ###########
/usr/bin/python -u  "~/scripts/september/testForPytables.py"

type(mtable)........  <class 'tables.Table.Table'>
mtable.nrows.......  105983
type(mcolumn)....  <class 'tables.Table.Column'>

index.size.......  1172

type(rtable).....  <class 'tables.nestedrecords.NestedRecArray'>
rtable.size().....  1172
rcolumn.size().. 1172