[英]Python: IndexError: list index out of range – trying to count two numbers from list in a for loop
[英]Trying to create a dictionary from a list of numbers, but list index is out of range
我正在嘗試創建一個函數來創建一個字典,其中出現的次數是鍵,每個鍵都有一個作為值出現多次的數字列表
它搞砸的部分是在線:
if num_list[i] not in num_dic.values():
或者也搞砸了:
if num_list.index(i) == num_list.index(j):
def createDic(num_list):
num_dic = {}
num_occurs = 0
for i in num_list:
if num_list[i] not in num_dic.values():
for j in num_list:
if num_list.index(i) == num_list.index(j):
num_occurs += 1
num_dic[num_occurs].append(num_list[i])
num_occurs = 0
return num_dic
您應該以不同的方式執行此操作,首先計算出現次數,然后將其轉換為字典:
>>> a = [1,1,2,3,4,4,4]
>>> from collections import Counter, defaultdict
>>> c = Counter(a)
>>> c
Counter({4: 3, 1: 2, 2: 1, 3: 1})
>>> occurences = defaultdict(list)
>>> for a,b in c.items() :
... occurences[b].append(a)
...
>>> occurences
defaultdict(<type 'list'>, {1: [2, 3], 2: [1], 3: [4]})
>>> dict(occurences)
{1: [2, 3], 2: [1], 3: [4]}
data = ["a", "b", "b", "c", "c", "c", "d", "d", "d"]
info = {}
for i in data:
count = data.count(i)
if count not in info:
info[count] = [i]
elif i not in info[count]:
info[count].extend(i)
print(info)
輸出:
{1: ['a'], 2: ['b'], 3: ['c', 'd']}
更好的解決方案,但使用導入:
from collections import Counter
data = ["a", "b", "b", "c", "c", "c", "d", "d", "d"]
info = {}
for o, c in Counter(data).items():
info[c] = [o] if c not in info else info[c] + [o]
print(info)
輸出:
{1: ['a'], 2: ['b'], 3: ['c', 'd']}
您沒有初始化num_dict
,您可以使用 defaultdict:
num_dict = defaultdict(列表)
num_list[i]
不會在num_dict.values()
因為values()
是列表而num_list[i]
是一個整數(你假設)
你用i
迭代列表,但然后認為它是索引而不是列表中的值,你應該用for i in range(len(num_list))
替換它(j 相同)
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