Hi, That is a little more complicated than I want, but it shows me the solution: Construct the array of the desired shape first, then fill it. data = [1.0, 3,0] keys = [('a',1),('b',2)] # Convert to arrays for indexing data_array = array(data1) key_array = empty(len(keys),dtype=tuple) key_array[:] = keys[:] inds = argsort(data) data_array[:] = data[inds] key_array[:] = keys[inds] Thanks! Michael. On 20 Jun 2007, at 4:57 AM, Francesc Altet wrote:

El dc 20 de 06 del 2007 a les 01:38 -0700, en/na Michael McNeil Forbes va escriure:

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Hi,

I have a list of tuples that I am using as keys and I would like to sort this along with some other arrays using argsort. How can I do this? I would like to do something like:

# These are constructed using lists because they accumulate using append() data = [1.0, 3,0] keys = [('a',1),('b',2)]

# Convert to arrays for indexing data = array(data1) keys = array(keys) # <--Converts to a 2d array rather than 1d array of tuples .

inds = argsort(data) data[:] = data[inds] keys[:] = keys[inds]

It seems there should be some way of specifying to the array constructor not to 'descend' (perhaps by specifying the desired dimensions of the final array or something) but I cannot find a nice way around this.

Here is a possible approach using recarrays:

In [54]:data = [3.0, 1.0] In [55]:keys = [('a',1),('b',2)] In [56]:tmp=numpy.array(keys, dtype="S1,i4") In [57]:dest=numpy.empty(shape=len(keys), dtype="S1,i4,f8") In [58]:dest['f0'] = tmp['f0'] In [59]:dest['f1'] = tmp['f1'] In [60]:dest['f2'] = data In [61]:dest Out[61]: array([('a', 1, 3.0), ('b', 2, 1.0)], dtype=[('f0', '|S1'), ('f1', '

If you want to retrieve the keys and data from the dest recarray afterwards, that's easy:

In [111]:data2=dest['f2'].tolist() In [112]:keys2=dest.getfield('S1,i4').tolist() In [113]:data2 Out[113]:[1.0, 3.0] In [114]:keys2 Out[114]:[('b', 2), ('a', 1)]

Cheers,

-- Francesc Altet | Be careful about using the following code -- Carabos Coop. V. | I've only proven that it works, www.carabos.com | I haven't tested it. -- Donald Knuth

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key_array = empty(len(keys),dtype=tuple) key_array[:] = keys[:]

the later two statements can also be written as:

key_array = array(keys, dtype=tuple)

These are not equivalent:

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keys = [('a',1),('b',2)] key_array = array(keys, dtype=tuple) key_array array([[a, 1], [b, 2]], dtype=object)

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key_array = empty(len(keys),dtype=tuple) key_array[:] = keys[:] key_array array([('a', 1), ('b', 2)], dtype=object)

Thanks, Michael.