检查一个元组的键在字典中重复了多少次？答案

【问题标题】：Check how many times a key of a tuple repeats itself in a dict?检查一个元组的键在字典中重复了多少次？
【发布时间】：2017-09-14 03:06:29
【问题描述】：

我有一本结构如下的字典：

{('key1','key2'): 50, ('key3','key4'): 70, ('key1','key5'): 90.....}

我想在我的字典中计算“key1”作为键元组中第一个单词出现的次数。

我开始编写下面提到的代码，但无法进一步思考：

  count = 0 
  leng = 0 
  i = 0 
  for key1,key2 in range(1,len(bigrams)):
      count = count +1 
      leng = leng + (bigrams.get((key1,key2),0))  
  print(count) 
  print(leng)

关于我应该如何进行的任何建议？

【问题讨论】：

一种方式sum(1 for k in x if k[0]=='key1') 假设你的字典被称为x。虽然@robs 的方式似乎更简洁。

标签： python dictionary tuples

【解决方案1】：

from collections import defaultdict

der = {('key1','key2'): 50, ('key3','key4'): 70, ('key1','key5'): 90}

b = defaultdict(int)
for item, ler in der:
    b[item] += 1
print b         ## defaultdict(int, {'key1': 2, 'key3': 1})
print b['key1'] ## [2]

Python tuple operations and count

【讨论】：

【解决方案2】：

我会使用 sum() 和生成器表达式来迭代键，依次测试每个键：

bigrams = {('key1','key2'): 50, ('key3','key4'): 70, ('key1','key5'): 90}

def number_of_times_key_appears_as_first_word(key, dictionary):
    return sum(k[0] == key for k in dictionary)

assert number_of_times_key_appears_as_first_word('key1', bigrams) == 2
assert number_of_times_key_appears_as_first_word('key3', bigrams) == 1
assert number_of_times_key_appears_as_first_word('key2', bigrams) == 0

【讨论】：

【解决方案3】：

你可以使用collections.Counter来统计key的每一部分，如下：

from collections import Counter
dic = {('key1','key2'): 50, ('key3','key4'): 70, ('key1','key5'): 90}
keys_0 = Counter(key[0] for key in dic.keys())
keys_1 = Counter(key[1] for key in dic.keys())

# keys_0 = Counter({'key1': 2, 'key3': 1})
# keys_1 = Counter({'key2': 1, 'key4': 1, 'key5': 1})

如果需要，您可以使用dict(Counter(...)) 将转换计数器对象键入到字典中

【讨论】：

【解决方案4】：

以下是所需的计数：

dict1 = {('key1','key2'): 50, ('key3','key4'): 70, ('key1','key5'): 90, ('key3','key1'): 90}
count = 0
for keys in dict1.keys():
    if 'key1' in keys:
        if (keys[0] == 'key1'):
            count = count + 1
print count

【讨论】：