Python-遍历整个列表并将其分配给dict

Question

text = "This is a test for my program"
new_dict = {}
text_list = text.split()

word_tester = 2
for word in text_list:
    word_tester = len(word)
    if len(word) == word_tester:
        new_dict[word_tester] = word

return new_dict

I am trying to build a program in python that goes through a list of strings and assigns them to a dict where the key is the amount of characters in that string and the value is the word itself (eg: 2 : be, to 3 : foo, bar). My program however only goes through and assigns some of the given list of strings. What can I do to get this to work?

Answer 1

I think you just need to be sure to split on the space. I ran this, and it works.

text = "This is a test for my program"
text_list = text.split(" ")
new_dict = {}
for word in text_list:
    if len(word) in new_dict and word not in new_dict[len(word)]:
        new_dict[len(word)].append(word)
    else:
        new_dict[len(word)] = [word]

#print(new_dict)
#{1: ['a'], 2: ['is', 'my'], 3: ['for'], 4: ['This', 'test'], 7: ['program']}
return new_dict

Answer 2

#1

text = "This is a test for my program"
final_dct = {len(word):word for word in text.split() if len(word)==len(word_tester)}

#2
text = "This is a test for my program"
new_dict = {}
text_list = text.split()


for word in text_list:
    if len(word) in new_dict and word not in new_dict[len(word)]:
        new_dict[len(word)].append(word)
    else:
        new_dict[len(word)] = [word]

return new_dict

Answer 3

I think it would be as simple as:

for word in text_list:
    new_dict[len(word)] = word

Note that in this dictionary, the key 4 is assigned to test, not this, because only one value can be assigned per key. To make the value a list in this case, you could use:

for word in text_list:
    if len(word) in new_dict:
        new_dict[len(word)].append(word)
    else:
        new_dict[len(word)] = [word]

Answer 4

The problem is that a key can only have one value so you overwrite it every time you have a word with a given length. To remedy this you could store a list of strings as the dictionary value instead of a single string, as suggested in another example.

One handy tool from the collections module is the defaultdict , which lets you define a default entry if a key doesn't already have a value. A common use case is to start keys out with an empty list using defaultdict(list) . This saves you from having to check if a key doesn't exist yet and initializing it to an empty list manually. Incorporating this into your example, you would get:

from collections import defaultdict

text = "This is a test for my program"
new_dict = defaultdict(list) # a dictionary whose default value is an empty list
text_list = text.split()

for word in text_list:
    # append this word to the list of words with the same length
    new_dict[len(word)].append(word)

return new_dict