You, know, float are inmutable objects, and then 'float(f)' just returns a new reference to 'f' is 'f' is (exactly) of type 'float'
In [1]: f = 1.234 In [2]: f is float(f) Out[2]: True I do not remember right now the implementations of comparisons in core Python, but I believe the 'in' operator is testing first for object identity, and then 'np.nan in [np.nan]' then returns True, and then the fact that 'np.nan==np.nan' returns False is never considered. On Fri, Sep 19, 2008 at 1:59 PM, Alan G Isaac <[EMAIL PROTECTED]> wrote: > Might someone explain this to me? > > >>> x = [1.,np.nan] > >>> np.nan in x > True > >>> np.nan in np.array(x) > False > >>> np.nan in np.array(x).tolist() > False > >>> np.nan is float(np.nan) > True > > Thank you, > Alan Isaac > > > _______________________________________________ > Numpy-discussion mailing list > Numpy-discussion@scipy.org > http://projects.scipy.org/mailman/listinfo/numpy-discussion > -- Lisandro Dalcín --------------- Centro Internacional de Métodos Computacionales en Ingeniería (CIMEC) Instituto de Desarrollo Tecnológico para la Industria Química (INTEC) Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) PTLC - Güemes 3450, (3000) Santa Fe, Argentina Tel/Fax: +54-(0)342-451.1594 _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
