count_string_occurrences 文字出現的次數

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This exercise is to show you how to count your string occurrences, or how many duplicated value. 我想分享如何找估重複文字次數。

iterate through list, and store in dictionary

[方法一] 基本 loop 把它存在 dictionary

output: {'James': 1, 'Kelly': 2, 'Sammie': 1

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listofName=['James','Kelly', 'Sammie', 'Kelly']
dictcollect={}
for name in listofName:
    if name in dictcollect:
        dictcollect[name]+=1

    else:
        dictcollect[name]=1
print(dictcollect)

其實可以寫成更簡短方式，其實跟上面方式一樣

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listofName=['James','Kelly', 'Sammie', 'Kelly']
dictcollect={}
for name in listofName:
    dictcollect[name]=dictcollect.get(name,0)+1
print(dictcollect)

如果沒出現就離開，出現就會+1，也可以這樣做 1+dictcollect.get(name,0)。

dictcollect.get(name, 0) checks if the name already exists as a key in the dictionary.
If it exists, the current count is retrieved.
If it doesn’t exist, 0 is returned.

[方法二] collection 裡面的 count

也可以利用 collection 方式來算，要先匯入 nodule from collection import count

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from collections import Counter
listofName=['James','Kelly', 'Sammie', 'Kelly']
namecounting=Counter(listofName) #collections.Counter
print(namecounting)
#Counter({'Kelly': 2, 'James': 1, 'Sammie': 1})

output: Counter({'Kelly': 2, 'James': 1, 'Sammie': 1})

如果想轉成 dict:

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#convert to dict
print(dict(namecounting))
#{'James': 1, 'Kelly': 2, 'Sammie': 1}

#conver to list
print(list(namecounting))
#['James', 'Kelly', 'Sammie']

output: {'James': 1, 'Kelly': 2, 'Sammie': 1}