Binary string search in Python 3.x

问题

I am having trouble getting this binary sort to work. I get syntax errors at lower_bound and in other places. I know it is something obvious but I am getting to the desk flipping point. Can someone help me to get this to run clearly, I know this is basic stuff but I am fairly new to this.

def main():
    sortNames()
    binarySearch()


def sortNames():
    global names
    names = ["Chris Rich", "Ava Fischer",  "Bob White", "Danielle Porter", "Gordon Pike", "Hannah Beauregard", "Matt Hoyle", "Ross Harrison", "Sasha Ricci", "Xavier Adams"]
    names.sort()


def binarySearch():
    global names, found, nameSearch, lower_bound, middle_pos, upper_bound
    nameSearch = string(input("What name are you looking for?")
    lower_bound = 0
    upper_bound = len(names)-1
    found = False
    while lower_bound <= upper_bound and not found:
        middle_pos = (lower_bound+upper_bound) // 2
        if name_list[middle_pos] < nameSearch:
            lower_bound = middle_pos + 1
        elif name_list[middle_pos] > nameSearch:
            upper_bound = middle_pos - 1
        else:
            found = True

    if found:
        print("The name is at position", middle_pos)
    else:
        print("The name was not in the list.")                               


main()

回答1:

You forgot to add the last closing parenthesis on the preceding line:

nameSearch = string(input("What name are you looking for?")
#               1--^  2--^                             2--^

Also, you didn't define the function string(). Not that it is needed, input() returns a string already.

After that, I see an error for name_list, but presumably you have that list defined outside of the code posted here.

回答2:

names = ["Chris Rich", "Ava Fischer",  "Bob White",\
         "Danielle Porter", "Gordon Pike", "Hannah Beauregard",\
         "Matt Hoyle", "Ross Harrison", "Sasha Ricci", "Xavier Adams"]

def sortNames():
    global names
    names.sort()

def binarySearch():
    global names, found, nameSearch, lower_bound, middle_pos, upper_bound

    nameSearch = raw_input("What name are you looking for?")
    lower_bound = 0
    upper_bound = len(names)-1
    found = False
    while lower_bound <= upper_bound and not found:
        middle_pos = (lower_bound+upper_bound) // 2
        if names[middle_pos] < nameSearch:
            lower_bound = middle_pos + 1
        elif names[middle_pos] > nameSearch:
            upper_bound = middle_pos - 1
        else:
            found = True
    if found:
        print("The name is at position", middle_pos)
    else:
        print("The name was not in the list.")                           

def main():
        sortNames()
        binarySearch()


if __name__ == "__main__":
    main()

Output

anukalp@anukalp-Latitude-E6400:~$ python del1.py
What name are you looking for?Ross Harrison
('The name is at position', 7)

来源：https://stackoverflow.com/questions/19896239/binary-string-search-in-python-3-x

标签

python

sorting

python-3.x

binary-search