On 5/21/14, Siegfried Gonzi <siegfried.go...@ed.ac.uk> wrote: > Please would anyone tell me the following is an undocumented bug > otherwise I will lose faith in everything: > > == > import numpy as np > > > years = [2004,2005,2006,2007] > > dates = [20040501,20050601,20060801,20071001] > > for x in years: > > print 'year ',x > > xy = np.array([x*1.0e-4 for x in dates]).astype(np.int) > > print 'year ',x > == > > Or is this a recipe to blow up a power plant? >
This is a "wart" of Python 2.x. The dummy variable used in a list comprehension remains defined with its final value in the enclosing scope. For example, this is Python 2.7: >>> x = 100 >>> w = [x*x for x in range(4)] >>> x 3 This behavior has been changed in Python 3. Here's the same sequence in Python 3.4: >>> x = 100 >>> w = [x*x for x in range(4)] >>> x 100 Guido van Rossum gives a summary of this issue near the end of this blog: http://python-history.blogspot.com/2010/06/from-list-comprehensions-to-generator.html Warren > Thanks, > Siegfried > > -- > The University of Edinburgh is a charitable body, registered in > Scotland, with registration number SC005336. > > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
