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问题:
I have a numpy array that looks like this:
[[41.743617 -87.626839] [41.936943 -87.669838] [41.962665 -87.65571899999999]]
I want to round the numbers in the array to two decimal places, or three. I tried using numpy.around and numpy.round, but both of them give me the following error:
File "/Library/Python/2.7/site-packages/numpy-1.8.0.dev_3084618_20130514-py2.7-macosx-10.8-intel.egg/numpy/core/fromnumeric.py", line 2452, in round_ return round(decimals, out) AttributeError: rint
i used numpy.around(x, decimals = 2) and numpy.round(x,decimals=2)
Am I doing something wrong? Is there any other way to do this efficiently for a large array?
回答1:
You cannot round numpy arrays that are objects, this can be changed with astype as long as your array can be safely converted to floats:
>>> a = np.random.rand(5).astype(np.object) >>> a array([0.5137250555772075, 0.4279757819721647, 0.4177118178603122, 0.6270676923544128, 0.43733218329094947], dtype=object) >>> np.around(a,3) Traceback (most recent call last): File "", line 1, in File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/numpy/core/fromnumeric.py", line 2384, in around return round(decimals, out) AttributeError: rint >>> np.around(a.astype(np.double),3) array([ 0.514, 0.428, 0.418, 0.627, 0.437])
You will receive similar errors with string, unicode, void, and char type arrays.
回答2:
You could do something like this:
numbers=[22.2,99.123,1213.1230] newnumbers=[] for n in numbers: newnumbers.append(round(n)) #for comparison print numbers print newnumbers
回答3:
numpy.around should work on a list of lists:
>>> import numpy as np >>> arr = [[41.743617, -87.626839], [41.936943, -87.669838], [41.962665, -87.65571899999999]] >>> >>> np.around(arr, decimals=2) array([[ 41.74, -87.63], [ 41.94, -87.67], [ 41.96, -87.66]]) >>> np.round(arr, decimals=2) array([[ 41.74, -87.63], [ 41.94, -87.67], [ 41.96, -87.66]])
However, note that it doesn't work on python longs. In fact it gives the same error you reported:
>>> np.round(3892438942893489234899848939) Traceback (most recent call last): File "", line 1, in File "/Users/csaftoiu/work/venv/lib/python2.7/site-packages/numpy/core/fromnumeric.py", line 2401, in round_ return _wrapit(a, 'round', decimals, out) File "/Users/csaftoiu/work/venv/lib/python2.7/site-packages/numpy/core/fromnumeric.py", line 38, in _wrapit result = getattr(asarray(obj),method)(*args, **kwds) AttributeError: rint
What seems to be happening is that numpy can't convert some of the numbers in your python list to one of its data types. If it's a long then it's not a problem because it's already rounded, but you'll have to work around it.
