This community-built FAQ covers the “Finding Duplicates” exercise from the lesson “Linear Search: Python”.
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Search Algorithms
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What is this supposed to mean? Is this Venus, Ankh, female or copper? And why here?
1 Like
You typed it wrong, it’s meant to be an up arrow.
This algorithm works in theory, but unfortunately the result that is given by the algorithm only shows the first instance of New York city and not the second one. No error is raised, and the for loop stops when we don’t want it to.
# Search list and target value
tour_locations = [ "New York City", "Los Angeles", "Bangkok", "Istanbul", "London", "New York City", "Toronto"]
target_city = "New York City"
#Linear Search Algorithm
def linear_search(search_list, target_value):
matches = []
for idx in range(len(search_list)):
if search_list[idx] == target_value:
matches.append(idx)
if len(matches) != 0:
return matches
else:
raise ValueError("{0} not in list".format(target_value))
#Function call
tour_stops = linear_search(tour_locations, target_city)
print(tour_stops)
We get [0] as a result, when really we should be getting [0,5] since New York City is in index 0 and 5 in the list.
Please help me understand what is going on, and how the algorithm can be modified to include the second instance.
You could remove the return and raising the error from the loop,
so that the loop continues to run after the first match,
and put return matches outside the loop (after the loop)
If you want to raise an error if there’s no matches,
you could have
if len(matches) == 0: # no matches (nothing in list)
raise ValueError("{0} not in list".format(target_value))
outside the loop, but before the return
