I use record arrays extensively with python datetimes, which works if
you pass in a list of lists of data with the names. numpy can
accurately infer the dtypes and create a usable record array. Eg,
import datetime
import numpy as np
rows = [ [datetime.date(2001,1,1), 12, 23.],
[datetime.date(2002,1,1), 10, 13.],
[datetime.date(2003,1,1), -2, 1.],
]
r1 = np.rec.fromrecords(rows, names='a,b,c')
print r1.dtype
prints out: [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
but if I want to speed things up by providing the dtype, numpy raises
ValueError:
dtype = [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
r2 = np.rec.fromrecords(rows, dtype=dtype)
/home/titan/johnh/test.py
12 dtype = [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
13
---> 14 r2 = np.rec.fromrecords(rows, dtype=dtype)
15
16
/home/titan/johnh/dev/lib/python2.4/site-packages/numpy/core/records.pyc
in fromrecords(recList, dtype, shape, formats, names, titles, aligned,
byteorder)
610
611 try:
--> 612 retval = sb.array(recList, dtype=descr)
613 except TypeError: # list of lists instead of list of tuples
614 if (shape is None or shape == 0):
ValueError: Setting void-array with object members using buffer.
WARNING: Failure executing file: <test.py>
Running from svn HEAD:
In [2]: numpy.__version__
Out[2]: '2.0.0.dev8480'
Here is a complete script::
import datetime
import numpy as np
rows = [ [datetime.date(2001,1,1), 12, 23.],
[datetime.date(2002,1,1), 10, 13.],I use record arrays
extensively with python datetimes, which works if you pass in a list
of lists of data with the names. numpy can accurately infer the
dtypes and create a usable record array. Eg,
import datetime
import numpy as np
rows = [ [datetime.date(2001,1,1), 12, 23.],
[datetime.date(2002,1,1), 10, 13.],
[datetime.date(2003,1,1), -2, 1.],
]
r1 = np.rec.fromrecords(rows, names='a,b,c')
print r1.dtype
prints out: [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
but if I want to speed things up by providing the dtype, numpy raises
ValueError:
dtype = [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
r2 = np.rec.fromrecords(rows, dtype=dtype)
/home/titan/johnh/test.py
12 dtype = [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
13
---> 14 r2 = np.rec.fromrecords(rows, dtype=dtype)
15
16
/home/titan/johnh/dev/lib/python2.4/site-packages/numpy/core/records.pyc
in fromrecords(recList, dtype, shape, formats, names, titles, aligned,
byteorder)
610
611 try:
--> 612 retval = sb.array(recList, dtype=descr)
613 except TypeError: # list of lists instead of list of tuples
614 if (shape is None or shape == 0):
ValueError: Setting void-array with object members using buffer.
WARNING: Failure executing file: <test.py>
Running from svn HEAD:
In [2]: numpy.__version__
Out[2]: '2.0.0.dev8480'
Here is a complete script::
import datetime
import numpy as np
rows = [ [datetime.date(2001,1,1), 12, 23.],
[datetime.date(2002,1,1), 10, 13.],
[datetime.date(2003,1,1), -2, 1.],
]
r1 = np.rec.fromrecords(rows, names='a,b,c')
print r1.dtype
dtype = [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
r2 = np.rec.fromrecords(rows, dtype=dtype)
[datetime.date(2003,1,1), -2, 1.],
]
r1 = np.rec.fromrecords(rows, names='a,b,c')
print r1.dtype
dtype = [('a', '|O4'), ('b', '<i4'), ('c', '<f8')]
r2 = np.rec.fromrecords(rows, dtype=dtype)
I filed a ticket on the tracker:
http://projects.scipy.org/numpy/ticket/1544
Thanks!
JDH
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