ó ,µ[c @s˜dZddlZddlZddljZddlZd„Ze dkr”eƒZ dGHdej e ƒej e ƒfGHej ƒZxe D]ZejeƒqWxFe jdeƒD]2\ZZZedd krşejeeƒqşqşWejd dƒgeD]Zeejeƒƒ^qZejee jd geD]Ze je^qAd edeƒejddƒejddƒej ƒndS(s  =========== Knuth Miles =========== `miles_graph()` returns an undirected graph over the 128 US cities from the datafile `miles_dat.txt`. The cities each have location and population data. The edges are labeled with the distance between the two cities. This example is described in Section 1.1 in Knuth's book (see [1]_ and [2]_). References. ----------- .. [1] Donald E. Knuth, "The Stanford GraphBase: A Platform for Combinatorial Computing", ACM Press, New York, 1993. .. [2] http://www-cs-faculty.stanford.edu/~knuth/sgb.html i˙˙˙˙NcCs‡ddl}|jddƒ}tjƒ}i|_i|_g}x>|jƒD]0}|jƒ}|jdƒrvqOnt j dƒ}|j |ƒrŜ|j ƒ}xÜ|D]0}|j ||| dt|ƒƒ| d} q§WqOd} |j d ƒ\}} |jd |ƒ| j d ƒ\} } | j d ƒ\} }|j|ƒt|ƒ d t| ƒdf|j|s2    '    "(