[英]How to write a alphabet bigram (aa, ab, bc, cd … zz) frequency analysis counter in python?
這是我當前的代碼,它打印出輸入文件中每個字符的頻率。
from collections import defaultdict
counters = defaultdict(int)
with open("input.txt") as content_file:
content = content_file.read()
for char in content:
counters[char] += 1
for letter in counters.keys():
print letter, (round(counters[letter]*100.00/1234,3))
我希望它只打印字母(aa,ab,ac ..zy,zz)的雙字母組的頻率,而不要打印標點符號。 這個怎么做?
您可以圍繞當前代碼進行構建以處理對。 通過添加另一個變量來跟蹤2個字符而不是僅僅1個字符,並使用檢查來消除非字母。
from collections import defaultdict
counters = defaultdict(int)
paired_counters = defaultdict(int)
with open("input.txt") as content_file:
content = content_file.read()
prev = '' #keeps track of last seen character
for char in content:
counters[char] += 1
if prev and (prev+char).isalpha(): #checks for alphabets.
paired_counters[prev+char] += 1
prev = char #assign current char to prev variable for next iteration
for letter in counters.keys(): #you can iterate through both keys and value pairs from a dictionary instead using .items in python 3 or .iteritems in python 2.
print letter, (round(counters[letter]*100.00/1234,3))
for pairs,values in paired_counters.iteritems(): #Use .items in python 3. Im guessing this is python2.
print pairs, values
(免責聲明:我的系統上沒有python2。如果代碼中存在問題,請通知我。)
有一種更有效的方法來統計二部圖:使用Counter
。 首先閱讀文本(假設文本不太大):
from collections import Counter
with open("input.txt") as content_file:
content = content_file.read()
過濾掉非字母:
letters = list(filter(str.isalpha, content))
您可能也應該將所有字母都轉換為小寫字母,但這取決於您:
letters = letters.lower()
用剩余的字母建立一個zip文件,將其移動一個位置,然后計算兩圖:
cntr = Counter(zip(letters, letters[1:]))
規范字典:
total = len(cntr)
{''.join(k): v / total for k,v in cntr.most_common()}
#{'ow': 0.1111111111111111, 'He': 0.05555555555555555...}
通過更改計數器,可以輕松地將解決方案推廣到三邊形等。
cntr = Counter(zip(letters, letters[1:], letters[2:]))
如果您使用的是nltk
:
from nltk import ngrams
list(ngrams('hello', n=2))
[OUT]:
[('h', 'e'), ('e', 'l'), ('l', 'l'), ('l', 'o')]
進行計數:
from collections import Counter
Counter(list(ngrams('hello', n=2)))
如果您想要python本機解決方案,請查看:
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