Stefan van der Walt wrote: > On Fri, Sep 22, 2006 at 02:17:57AM -0500, Robert Kern wrote: > >>> According to the putmask docstring: >>> >>> a.putmask(values, mask) sets a.flat[n] = v[n] for each n where >>> mask.flat[n] is true. v can be scalar. >>> >>> This would mean that 'w' is not of the right length. >>> >> There are 4 true values in m and 4 values in w. What's the wrong >> > length? > > The way I read the docstring, you use putmask like this: > > In [4]: x = N.array([1,2,3,4]) > > In [5]: x.putmask([4,3,2,1],[1,0,0,1]) > > In [6]: x > Out[6]: array([4, 2, 3, 1]) > > >> >> Out[9] and Out[18] should have been the same, but elements 6 and 9 are >> flipped. >> It's pretty clear that this is a bug in .putmask(). >> > > Based purely on what I read in the docstring, I would expect the above to do > > x[0] = w[0] > x[6] = w[6] > x[9] = w[9] > x[11] = w[11] > > Since w is of length 4, you'll probably get indices modulo 4: > > w[6] == w[2] == -3 > w[9] == w[1] == -2 > w[11] == w[3] == -4 > > Which seems to explain what you are seeing. >
Yes, this does explain what you are seeing. It is the behavior of Numeric's putmask (where this method came from). It does seem counter-intuitive, and I'm not sure what to do with it. In some sense putmask should behave the same as x[m] = w. But, on the other-hand, was anybody actually using the "modular" indexing "feature" of "putmask". Here are our options: 1) "fix-it" and risk breaking code for people who used putmask and the modular indexing "feature," 2) Get rid of it as a method (and keep it as a function so that oldnumeric can use it.) 3) Keep everything the way it is. -Travis ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Numpy-discussion mailing list Numpy-discussion@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/numpy-discussion
