import numpy as np
from itertools import izip

def normalize_file(filename):
    """
    Normalizes file:
    If nodes are not numbered 0 to number_of_nodes - 1, then prints
    normalized version of dataset in the same directory
    """
    #Read number of unique node identifications
    nodes = []
    with open(filename, "r") as f:
        for line in f:
            if "#" not in line:
                node_1, node_2 = line.split()
                nodes.append(node_1); nodes.append(node_2)
        uniq_nodes = np.unique(nodes)

    #Hash nodes to an index between 0 and number_of_nodes - 1
    hash_nodes = {}
    for idx, node in enumerate(uniq_nodes):
        hash_nodes[node] = idx

    #Write to file
    with open(filename[:-4]+"normalize.txt", "w") as g:
        with open(filename, "r") as f:
            for line_f in f:
                f_node_1, f_node_2 = line_f.split()
                g_node_1 = hash_nodes[f_node_1]
                g_node_2 = hash_nodes[f_node_2]
                g.write(str(g_node_1)+" "+str(g_node_2)+"\n")