GfmLinks.py

def checkNode(node, graph):
    '''Checks whether a node is in a graph'''
    if node in graph:
        return(True)
    else:
        return (False)
        
def fromLinks(links):
    '''
    Takes a list of links in the form of tuples, or lists, 
    with two elements describing the connected nodes and returns a graph in the form of a dictionary.
    
    Exampple input: [(1,2),(1,4),(2,3),(3,4)] or [[1,2],[1,4],(,3),(3,4)]
    
    Example output (fm input): {1:[2,4],2:[1,3],3:[2,4],4:[1,3]}
    '''
    ## set up an empty dictionary
    graph = {}
    ##iterate thru the input nodes
    for link in links:
        ##Check if each node is in the graph, if it isnt add it.
        for node in link:
            if not checkNode(node, graph):
                graph[node] = []
        ##for both ends of the node add the link to the other
        graph[link[0]].append(link[1])
        graph[link[1]].append(link[0])
    return graph
##tests

assert(fromLinks([(1,2),(1,4),(2,3),(3,4)]) == {1:[2,4],2:[1,3],3:[2,4],4:[1,3]})
assert(fromLinks([[1,2],[1,4],[2,3],[3,4]]) == {1:[2,4],2:[1,3],3:[2,4],4:[1,3]})
## these should run without error,