Write a function that makes another function returns a List instead of function

Question

This are previously defined functions

def make_service(service_data, service_code):
    routes = []

    directions = list(set(map(lambda entry: entry[1], service_data)))  #['1', '2']

    for direction in directions:
        #'1' but if it is '2' then 
        #[('106', '2', '1', '03239'),...('106', '2', '51', '43009')] will be returned for nxt line

        one_direction = filter(lambda entry: entry[1] == direction, service_data)
         #if '1' then [('106', '1', '1', '43009')..('106', '1', '48', '03219')]

        route = map(lambda thing: thing[3], one_direction) #['43009', '43179',..'03218', '03219']

        routes.append(route) #[['43009', '43179',..'03218', '03219']] 

    return lambda t: service_code if t == 0 else (directions if t == 1 else routes)
    # a function is returnrf here ! 


service_106 = make_service(service_106_data, "106")

service_106_data = filter_routes(smrt_routes, "106") 
#[('106', '1', '1', '43009'), ...,('106', '1', '48', '03219'), ('106', '2', '1', '03239'),...('106', '2', '51', '43009')]

So I am suppose to write a function here that returns

[['43009', '43179',..'03218', '43009']]

I have tried:

def get_routes(service):
    return map(lambda x: x, service) # I was thinking that 

service_106_routes = get_routes(service_106)
print(service_106_routes)  # I should get  [['43009', '43179',..'03218', '43009']]

How do I get write a function that extracts [['43009', '43179',..'03218', '43009']] from make_service that actually returns a function lambda t? I don't really know how to start writing my code though... Do I start with t?

jonrsharpe · Accepted Answer · 2014-03-12 13:57:09Z

2

make_service returns a simple lambda function with one argument; t. This lambda function in turn returns either:

service_code (t==0);
directions (t==1); or
routes (any other value of t).

Therefore once you have this function you can access any of these values by providing the appropriate argument, e.g.

106_service_code = service_106(0)

answered Mar 12, 2014 at 13:57

jonrsharpe

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1 Comment

user3398505 Over a year ago

Thank You !! I got it ! it should be any value that's not 0 or 1 which return the list that I want!

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