New subject: numarray.records - get/set item

Dec. 4, 2003

      My situation where I got onto this, is having one field named 'mmm'
("MinMaxMean") being an 3 element array.
Now, to assign the values first I tried:
self.hdrArray = makeHdrArray(self.h)   #this makes the record array
self.hdr = self.hdrArray[0].field              #this is my shortcut to the
bound member function
   # it essentially is a solution (hack) for the getitem part
   # but regarding setitem I had to learn that "assigning to a function" is
illigal in Python - as opposed to C++
#so to do assignment  I need to do:
self.hdr('mmm')[0], self.hdr('mmm')[1], self.hdr('mmm')[2] = (mi,ma,av)

now that I'm looking at it,
self.hdrArray[0].setfield('mmm', (mi,ma,av))
would probably be better...

How about adding an attribute 'f' which could serve as a "proxy" to allow:
myRec.f.mmm = (mi,ma,av)
and maybe even additionally:
myRec.f['mmm'] = (mi,ma,av)

Regards,
Sebastian

----- Original Message ----- 
From: "Perry Greenfield" <perry@stsci.edu>
To: "Sebastian Haase" <haase@msg.ucsf.edu>;
<numpy-discussion@lists.sourceforge.net>
Sent: Thursday, December 04, 2003 3:08 PM
Subject: RE: [Numpy-discussion] numarray.records - get/set item
...
...
Hi,
Is it maybe a good idea to add this to the definition of 'class Record'
class Record:
    """Class for one single row."""
<snip>
    def __getitem__(self, fieldName):
        return self.array.field(fieldName)[self.row]
    def __setitem__(self, fieldName, value):
        self.array.field(fieldName)[self.row] = value
I don't know  about the implications if  __delitem __  and so on are not
defined.
I just think it would look quite nice to say
myRecArr[0]['mmm'] = 'hallo'
as opposed to
myRecArr[0].setfield('mmm',  'hallo')
Actually I would even like
myRecArr[0].mmm = 'hallo'
This should be possible by defining __setattr__.
It would obviously only work for fieldnames that do not contain '.' or '
'
or ...
Any comments ?
We've had many internal discussions about doing this. The latter was
considered a problem because of possible name collisions of field
names with other attributes or methods. The former is not bothered
by this problem, but we decided to be conservative on this and see
how strong the need was. We are interested in other opinions.
Perry

Fw: [Numpy-discussion] numarray.records - get/set item

Sebastian Haase

Sebastian Haase

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