从txt文件创建的列表中编辑字典列表

Question

I am trying to exclude and remove some dictionaries from a list. I have searched for awhile through the site and haven't found anything specific to this. The list of dictionaries was created from a txt file located: http://s000.tinyupload.com/?file_id=48953557772434487729

I'm trying to sort out and exclude the things I don't need. I thought my syntax was right, but apparently not.

I only included necessary code to cut down on the clutter. I am having problems at the action_genre point and excluding and deleting the dictionaries there. When prompted enter "s" and then "a" to access those two menus.

def load_movies():
    global movies_list
    movies_list= []
    file_ref = open("movies.txt", 'r')
    line = file_ref.readline()
    for line in file_ref:
        line = line.strip()
        current = {}
        if line == '':
            break
        movie_data = line.split("\t")
        current["title"] = movie_data[0]
        current["year"] = movie_data[1]
        current["length"] = movie_data[2]
        current["rating"] = movie_data[3]
        current["action"] = int(movie_data[4][0]) == 1
        current["animation"] = int(movie_data[4][1]) == 1
        current["comedy"] = int(movie_data[4][2]) == 1
        current["drama"] = int(movie_data[4][3]) == 1
        current["documentary"] = int(movie_data[4][4]) == 1
        current["romance"] = int(movie_data[4][5]) == 1
        movies_list.append(current)
        del current
    file_ref.close()


def menu():
    movie_selector =("Movie Selector - Please enter an option below:\nL - List all movies\nY - List all movies by year\n"
                "T - Search by title\nS - Search by genre, rating, and maximum length\nQ - Quit the program\nOption:")
    movie_selector_input = input(movie_selector).upper()

    if movie_selector_input == "L":
        list_movies()
    if movie_selector_input == "Y":
        list_by_year()
    if movie_selector_input == "T":
        search_by_title()
    if movie_selector_input == "S":
        search()
    if movie_selector_input == "Q":
        print("Thanks for using my program! Goodbye.")
        exit()
else:
    print("Invalid input")
    print("Please try again")
    print()
    return menu()

def search():
    genre_input = input("Please make a selection from the following genres.\n(Action(A), Animation(N), Comedy(C), "
                    "Drama(D), Documentary(O), or Romance(R)):").lower()
    if genre_input == 'a':
        action_genre()
    elif genre_input == 'n':
        animation_genre()
    elif genre_input == 'c':
        comedy_genre()
    elif genre_input == 'd:':
        drama_genre()
    elif genre_input == 'o':
        documentary_genre()
    elif genre_input == 'r':
        romance_genre()
    else:
        print("Invalid genre")
        print()
        menu()

#this is where I can't get the syntax to work
def action_genre():
    for current in movies_list:
        if current["action"] == "False":
            del current
            break
        for i in movies_list:#using this to test output
            print(i)

load_movies()
menu()

I'm narrowing down the list by excluding things that don't fit the parameters. In the action_genre function, I'm trying to delete all the dictionaries that don't equal current["action"] == True. I've tried using "True" and "False" as strings, as well as the bools True and False for comparisons, and still an error. Unfortunately, I have to use the Boolean logic per my professors directions.

His eg: Professor's example. Apparently since I'm new I can't embed images. :/

I'm in programming 101, so thank you for your patience as I learn this, and thank you in advance for the help.

Answer 1

You are trying to compare a string with a boolean . Look at the following:

a= 1==1
print a
True

print type(a)
<class 'bool'> # a is a boolean

b='True' #assign string 'True' to b
print type(b)
<class 'str'>

print a==b #compare boolean True to string 'True'
False

b = True # assign boolean True to b
print a==b #compare boolean True to boolean True
True

so you need if current["action"] == False instead of if current["action"] == "False"

Answer 2

Okay, so the issue runs a bit deeper than the if condition being incorrect. In get_action() you effictively do not modify the actual movies_list object, but rather the local variable current , as proven by this simple test:

def action_genre():
    for current in movies_list:
        print(current)
        if not current["action"]:
            del current
        print(current)

The second print(current) will result in an UnboundLocalError saying that current does not exist anymore, while in movies_list the entry it just deleted continues to exist. But in general, using del in loops indeed causes problems because that's how iterables and del itself behave. I encourage you to read up more on this on other sources or SO if you wish, like here .

Using the answer from the provided link above, we can use list comprehension to filter the movies:

def action_genre():
    filtered_movies_list = [movie for movie in movies_list if movie['action']]
    print(filtered_movies_list)

This creates a new list (so it does not modify movies_list ), which includes all dictionary entries where item['action'] == True .

I hope this helps.