Hi everybody, I would like to check if there has been made a decision on this ? I'm planning to use record arrays to access image data header-information and having an attribute 'f' like suggested is still my favorite way. Is anyone besides me using record arrays on memory-mapped buffers ? Thanks, Sebastian Haase ----- Original Message ----- From: "Sebastian Haase" <haase@msg.ucsf.edu> To: <numpy-discussion@lists.sourceforge.net> Sent: Thursday, December 04, 2003 4:27 PM Subject: Fw: [Numpy-discussion] numarray.records - get/set item
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
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