我正在阅读Jeol Grus的"Data Science from Scratch“,这本书距离我的大学数据结构课程已经过去了20多年。他被他编写代码的优雅方式所吸引。在第一章的例子中,我感兴趣的是将自己的字典附加到自身的数据结构- 'users‘。当我试图通过打印'users‘的内容来理解它在字典中的工作方式时,它会打印出该字典的无限循环。更令人惊讶的是,Python没有错误。但我还是不知道内容是什么。
搜索了一些文章,在Quora How do I nicely print a nested dictionary in Python?上找到了一篇,并理解了其中的内容。尽管我开始思考是否可以像下面这样,用指向字典或类似的指针,而不是重复的循环,以更简洁的风格打印出内容。有可能吗?
{"id": 0, "name": "Hero", "friend": [*users[1], *users[2]] }
{"id": 1, "name": "Dunn", "friend": [*users[2], *users[3]] }从零开始的数据科学示例
users = [
{ "id": 0, "name": "Hero"},
{ "id": 1, "name": "Dunn"},
{ "id": 2, "name": "Sue"},
{ "id": 3, "name": "Chi"},
{ "id": 4, "name": "Thor"},
{ "id": 5, "name": "Clive"},
{ "id": 6, "name": "Hicks"},
{ "id": 7, "name": "Devin"},
{ "id": 8, "name": "Kate"},
{ "id": 9, "name": "Klein"}
]
friendship = [(0,1), (0,2), (1,2), (1,3), (2,3), (3,4),
(4,5), (5,6), (5,7), (6,8), (7,8), (8,9)]
for user in users :
user["friends"] = []
for i, j in friendship :
users[i]["friends"].append(users[j])
users[j]["friends"].append(users[i])
def number_of_friends(user) :
""" how many friends does _user_ have """
return(len(user["friends"]))
total_connection = sum(number_of_friends(user)
for user in users)
num_users = len(users)
avg_connection = total_connection / num_users
# create a list (user_id, number_of_friends)
num_friends_by_id = [(user['id'], number_of_friends(user))
for user in users]打印输出
{'id': 0, 'name': 'Hero', 'friends': [{'id': 1, 'name': 'Dunn', 'friends': [{...}, {'id': 2, 'name': 'Sue', 'friends': [{...}, {...}, {'id': 3, 'name': 'Chi', 'friends': [{...}, {...}, {'id': 4, 'name': 'Thor', 'friends': [{...}, {'id': 5, 'name': 'Clive', 'friends': [{...}, {'id': 6, 'name': 'Hicks', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{...}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {...}]}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{'id': 6, 'name': 'Hicks', 'friends': [{...}, {...}]}, {...}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}]}]}]}]}, {'id': 3, 'name': 'Chi', 'friends': [{...}, {'id': 2, 'name': 'Sue', 'friends': [{...}, {...}, {...}]}, {'id': 4, 'name': 'Thor', 'friends': [{...}, {'id': 5, 'name': 'Clive', 'friends': [{...}, {'id': 6, 'name': 'Hicks', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{...}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {...}]}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{'id': 6, 'name': 'Hicks', 'friends': [{...}, {...}]}, {...}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}]}]}]}]}, {'id': 2, 'name': 'Sue', 'friends': [{...}, {'id': 1, 'name': 'Dunn', 'friends': [{...}, {...}, {'id': 3, 'name': 'Chi', 'friends': [{...}, {...}, {'id': 4, 'name': 'Thor', 'friends': [{...}, {'id': 5, 'name': 'Clive', 'friends': [{...}, {'id': 6, 'name': 'Hicks', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{...}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {...}]}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{'id': 6, 'name': 'Hicks', 'friends': [{...}, {...}]}, {...}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}]}]}]}]}, {'id': 3, 'name': 'Chi', 'friends': [{'id': 1, 'name': 'Dunn', 'friends': [{...}, {...}, {...}]}, {...}, {'id': 4, 'name': 'Thor', 'friends': [{...}, {'id': 5, 'name': 'Clive', 'friends': [{...}, {'id': 6, 'name': 'Hicks', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{...}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {...}]}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}, {'id': 7, 'name': 'Devin', 'friends': [{...}, {'id': 8, 'name': 'Kate', 'friends': [{'id': 6, 'name': 'Hicks', 'friends': [{...}, {...}]}, {...}, {'id': 9, 'name': 'Klein', 'friends': [{...}]}]}]}]}]}]}]}]}发布于 2020-04-12 20:55:17
尝试使用类而不是字典。
class Person:
def __init__(self, id, name):
self.id = id
self.name = name
self.friends = []
def __str__(self):
return "*users[" + str(id) + "]"https://stackoverflow.com/questions/61171727
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