Zack C Normal Mode

currency_converter.py

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+def convert(rates, value, a_from, a_to):
+    """This function is designed to take in the below arguments and return
+    the value in the specified currency.
+
+    rates = a list of tupleswith each tuple containing a currency code
+            you can convert from, a currency code you can convert to,
+            and a rate
+    value = the amount of money you'd like to exchange for
+    from = the currency code in the form of a string
+    to = the currency code you'd like the value in. also a string"""
+
+    if a_from == a_to:
+        return value
+
+    for list_from, list_to, list_rate in rates:
+        if list_from == a_from and list_to == a_to:
+            return round(value * list_rate, 3)
+
+        elif list_from == a_to and list_to == a_from:
+            return round(value / list_rate, 3)
+
+
+if __name__ == '__main__':
+    new_rates = [("JPY", "EUR", .0069),
+                 ("EUR", "USD", 1.35)]
+
+    print(convert(new_rates, 1, "JPY", "EUR"))

dijkstras_algorithm.py

@@ -0,0 +1,47 @@
+from collections import namedtuple
+
+
+inf = float('inf')
+Edge = namedtuple('Edge', 'start, end, cost')
+
+class Graph():
+    def __init__(self, edges):
+        self.edges = edges2 = [Edge(*edge) for edge in edges]
+        self.vertices = set(sum(([e.start, e.end] for e in edges2), []))
+
+    def dijkstra(self, source, dest):
+        assert source in self.vertices
+        dist = {vertex: inf for vertex in self.vertices}
+        previous = {vertex: None for vertex in self.vertices}
+        dist[source] = 0
+        q = self.vertices.copy()
+        neighbours = {vertex: set() for vertex in self.vertices}
+        for start, end, cost in self.edges:
+            neighbours[start].add((end, cost))
+
+        while q:
+            u = min(q, key=lambda vertex: dist[vertex])
+            q.remove(u)
+            if dist[u] == inf or u == dest:
+                break
+            for v, cost in neighbours[u]:
+                alt = dist[u] + cost
+                if alt < dist[v]:                   # Relax (u,v,a)
+                    dist[v] = alt
+                    previous[v] = u
+        s, u = [], dest
+        while previous[u]:
+            s.insert(0, u)
+            u = previous[u]
+        s.insert(0, u)
+        return s
+
+
+graph = Graph([("JPY", "EUR", .0069),
+               ("EUR", "USD", 1.35),
+               ])
+
+
+print(graph.dijkstra("JPY", "USD"))
+
+# Answer is .0092

test_currency_converter.py

@@ -0,0 +1,39 @@
+from currency_converter import convert
+
+
+rates = [("USD", "EUR", 0.74)]
+value = 1
+a_from = 'USD'
+a_to = 'EUR'
+
+def test_convert():
+    assert convert(rates, value, 'USD', 'USD') == 1
+
+def test_simple_conversion():
+    assert convert(rates, value, a_from, a_to) == .74
+
+def test_different_values():
+    assert convert(rates, 10, a_from, a_to) == 7.4
+    assert convert(rates, 50, a_from, a_to) == 37
+    assert int(convert(rates, 1.5, a_from, a_to)) == 1
+
+def test_reverse_lookup():
+    assert convert([("EUR", "USD", 0.74)], value, a_from, a_to) == 1.351
+
+def test_multiple_dif_rates():
+    new_rates = [("USD", "EUR", 0.74), ("EUR", "JPY", 145.949),
+                 ("USD", "MXN", 14.64)]
+
+    assert convert(new_rates, value, 'EUR', 'JPY') == 145.949
+    assert convert(new_rates, value, "JPY", "EUR") == .007
+    assert convert(new_rates, value, "JPY", "EUR") == .007
+    assert convert(new_rates, 500, "MXN", "USD") == 34.153
+
+def BROKEN_test_values_into_new_rates():
+    new_rates = [("USD", "EUR", 0.74), ("EUR", "JPY", 145.949)]
+
+    USD_to_EUR = convert(new_rates, value, "USD", "EUR")
+    EUR_to_JPY = convert(new_rates, USD_to_EUR, 'EUR', 'JPY')
+    JPY_to_USD = convert(new_rates, EUR_to_JPY, 'JPY', 'USD')
+
+    assert JPY_to_USD == 1