How to add columns to python arrays
mahs at telcopartners.com
Wed May 17 21:20:00 CEST 2006
Terry Reedy wrote:
> "CC" <chuangwoo at gmail.com> wrote in message
> news:1147882432.166728.207820 at j55g2000cwa.googlegroups.com...
>> I wanna compile a 6000x1000 array with python. The array starts from
>> 'empty', each time I get a 6000 length list, I wanna add it to the
>> exist array as a column vector. Is there any function to do so?
>> Or, I can add the list as a rows, if this is easier, and transpose the
>> whole array after all the rows are setup.
> Python does not come with a 2D array type either as a builtin type or as a
> standard library module. You can only simulate one with a sequence of
> sequences (list of lists, for instance). You could initialize as follows:
> aray = 
> for l6000 in source(): aray.append(l6000)
> While this will print as a list of rows, you are free to think of it as a
> list of columns.
> That said, I suspect you should use the 3rd party NumPy package which
> defines multiple-dimensional arrays of several base types.
> Terry Jan Reedy
If you're just looking for a multi-dimensional array type, and don't need
maximum speed or the vast range of array-processing that numpy offers, then
*pyarray* provides a pure-python single module solution.
the latest pyarray is available with tests and documentation at:
pyarray is a pure-Python implementation of a multi-dimensional array type.
pyarray.ListView and pyarray.ArrayView offer a substantial subset of
numpy.ArrayType functionality, by wrapping standard python 'list' and
Key features include:
* Views: all subscripting operations apart from individual cell access
access return views to existing 'live' data
* Extended Indexing: slicing, arbitrary 'takes', index arrays etc...
* Unlimited re-shaping: while still addressing one data-source
* Elementwise binary operations: all basic arithmetic and comparison
* Data broadcasting: allows assignment and binary operations between
views of different shapes
* Friendly __repr__: work safely with big arrays at the interactive prompt
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