使用pythonsortingWord频率计数
我必须使用python来计算文本中的单词频率。 我想在词典中保留单词，并为每个单词计数。
现在，如果我不得不按照出现的次数来sorting这些单词。 我可以用同一个词典来做，而不是使用一个新的字典，这个字典有作为字数和字数的关键字的关键字吗？
你可以使用相同的字典：
>>> d = { "foo": 4, "bar": 2, "quux": 3 } >>> sorted(d.items(), key=lambda item: item[1]) 第二行打印：
[('bar', 2), ('quux', 3), ('foo', 4)]
如果你只想要一个sorting的单词列表，做：
>>> [pair[0] for pair in sorted(d.items(), key=lambda item: item[1])]
该行打印：
['bar', 'quux', 'foo']
警告：这个例子需要Python 2.7或更高版本。
Python内置的Counter对象正是您所需要的。 计数单词甚至是文档中的第一个例子：
>>> # Tally occurrences of words in a list >>> from collections import Counter >>> cnt = Counter() >>> for word in ['red', 'blue', 'red', 'green', 'blue', 'blue']: ... cnt[word] += 1 >>> cnt Counter({'blue': 3, 'red': 2, 'green': 1})
如注释中所指定的， Counter需要一个迭代，所以上面的例子仅仅是为了说明，相当于：
>>> mywords = ['red', 'blue', 'red', 'green', 'blue', 'blue'] >>> cnt = Counter(mywords) >>> cnt Counter({'blue': 3, 'red': 2, 'green': 1})
您可以在Python 2.7 collections模块中defaultdict使用Counter 和 defaultdict 。 首先使用Counter来创build一个字典，其中每个字是一个关键的频率计数。 这是相当微不足道的。
其次， defaultdict可以用来创build一个反向或反向的字典，其中的键是发生的频率，相关的值是多次遇到的单词或单词的列表。 这是我的意思：
from collections import Counter, defaultdict wordlist = ['red', 'yellow', 'blue', 'red', 'green', 'blue', 'blue', 'yellow'] # invert a temporary Counter(wordlist) dictionary so keys are # frequency of occurrence and values are lists the words encountered freqword = defaultdict(list) for word, freq in Counter(wordlist).items(): freqword[freq].append(word) # print in order of occurrence (with sorted list of words) for freq in sorted(freqword): print('count {}: {}'.format(freq, sorted(freqword[freq])))
输出：
count 1: ['green'] count 2: ['red', 'yellow'] count 3: ['blue']
>>> d = {'a': 3, 'b': 1, 'c': 2, 'd': 5, 'e': 0} >>> l = d.items() >>> l.sort(key = lambda item: item[1]) >>> l [('e', 0), ('b', 1), ('c', 2), ('a', 3), ('d', 5)]
我刚刚写了一个类似的程序，在堆栈溢出家伙的帮助下：
from string import punctuation from operator import itemgetter N = 100 words = {} words_gen = (word.strip(punctuation).lower() for line in open("poi_run.txt") for word in line.split()) for word in words_gen: words[word] = words.get(word, 0) + 1 top_words = sorted(words.items(), key=itemgetter(1), reverse=True)[:N] for word, frequency in top_words: print ("%s %d" % (word, frequency))
要find这些项目的频率更容易，那么你们正在做。 如果你有一个列表中的所有单词（使用string拆分function很容易）。 然后：
#(Pseudo Python Code) listOfWords = inputString.split() # splits the words up from whitespace setOfWords = Set(listOfWords) # Gives you all the unique words (no duplicates) for each word in setOfWords #Count how many words are in the list print word + " appears: " + listOfWords.Count(word) + "times"
如果您需要额外的文本处理，可能需要将nltk （自然语言工具包）导入到您的项目中。 以下是一个使用JFK就职演说的例子：
import nltk speech_text = "Vice President Johnson, Mr. Speaker, Mr. Chief Justice, President Eisenhower, Vice President Nixon, President Truman, reverend clergy, fellow citizens: We observe today not a victory of party, but a celebration of freedom — symbolizing an end, as well as a beginning — signifying renewal, as well as change. For I have sworn before you and Almighty God the same solemn oath our forebears prescribed nearly a century and three-quarters ago. The world is very different now. For man holds in his mortal hands the power to abolish all forms of human poverty and all forms of human life. And yet the same revolutionary beliefs for which our forebears fought are still at issue around the globe — the belief that the rights of man come not from the generosity of the state, but from the hand of God. We dare not forget today that we are the heirs of that first revolution. Let the word go forth from this time and place, to friend and foe alike, that the torch has been passed to a new generation of Americans — born in this century, tempered by war, disciplined by a hard and bitter peace, proud of our ancient heritage, and unwilling to witness or permit the slow undoing of those human rights to which this nation has always been committed, and to which we are committed today at home and around the world. Let every nation know, whether it wishes us well or ill, that we shall pay any price, bear any burden, meet any hardship, support any friend, oppose any foe, to assure the survival and the success of liberty. This much we pledge — and more. To those old allies whose cultural and spiritual origins we share, we pledge the loyalty of faithful friends. United there is little we cannot do in a host of cooperative ventures. Divided there is little we can do — for we dare not meet a powerful challenge at odds and split asunder. To those new states whom we welcome to the ranks of the free, we pledge our word that one form of colonial control shall not have passed away merely to be replaced by a far more iron tyranny. We shall not always expect to find them supporting our view. But we shall always hope to find them strongly supporting their own freedom — and to remember that, in the past, those who foolishly sought power by riding the back of the tiger ended up inside. To those people in the huts and villages of half the globe struggling to break the bonds of mass misery, we pledge our best efforts to help them help themselves, for whatever period is required — not because the Communists may be doing it, not because we seek their votes, but because it is right. If a free society cannot help the many who are poor, it cannot save the few who are rich. To our sister republics south of our border, we offer a special pledge: to convert our good words into good deeds, in a new alliance for progress, to assist free men and free governments in casting off the chains of poverty. But this peaceful revolution of hope cannot become the prey of hostile powers. Let all our neighbors know that we shall join with them to oppose aggression or subversion anywhere in the Americas. And let every other power know that this hemisphere intends to remain the master of its own house. To that world assembly of sovereign states, the United Nations, our last best hope in an age where the instruments of war have far outpaced the instruments of peace, we renew our pledge of support — to prevent it from becoming merely a forum for invective, to strengthen its shield of the new and the weak, and to enlarge the area in which its writ may run. Finally, to those nations who would make themselves our adversary, we offer not a pledge but a request: that both sides begin anew the quest for peace, before the dark powers of destruction unleashed by science engulf all humanity in planned or accidental self-destruction. We dare not tempt them with weakness. For only when our arms are sufficient beyond doubt can we be certain beyond doubt that they will never be employed. But neither can two great and powerful groups of nations take comfort from our present course — both sides overburdened by the cost of modern weapons, both rightly alarmed by the steady spread of the deadly atom, yet both racing to alter that uncertain balance of terror that stays the hand of mankind's final war. So let us begin anew — remembering on both sides that civility is not a sign of weakness, and sincerity is always subject to proof. Let us never negotiate out of fear, but let us never fear to negotiate. Let both sides explore what problems unite us instead of belaboring those problems which divide us. Let both sides, for the first time, formulate serious and precise proposals for the inspection and control of arms, and bring the absolute power to destroy other nations under the absolute control of all nations. Let both sides seek to invoke the wonders of science instead of its terrors. Together let us explore the stars, conquer the deserts, eradicate disease, tap the ocean depths, and encourage the arts and commerce. Let both sides unite to heed, in all corners of the earth, the command of Isaiah — to “undo the heavy burdens, and [to] let the oppressed go free.”¹ And, if a beachhead of cooperation may push back the jungle of suspicion, let both sides join in creating a new endeavor — not a new balance of power, but a new world of law — where the strong are just, and the weak secure, and the peace preserved. All this will not be finished in the first one hundred days. Nor will it be finished in the first one thousand days; nor in the life of this Administration; nor even perhaps in our lifetime on this planet. But let us begin. In your hands, my fellow citizens, more than mine, will rest the final success or failure of our course. Since this country was founded, each generation of Americans has been summoned to give testimony to its national loyalty. The graves of young Americans who answered the call to service surround the globe. Now the trumpet summons us again — not as a call to bear arms, though arms we need — not as a call to battle, though embattled we are — but a call to bear the burden of a long twilight struggle, year in and year out, “rejoicing in hope; patient in tribulation,”² a struggle against the common enemies of man: tyranny, poverty, disease, and war itself. Can we forge against these enemies a grand and global alliance, North and South, East and West, that can assure a more fruitful life for all mankind? Will you join in that historic effort? In the long history of the world, only a few generations have been granted the role of defending freedom in its hour of maximum danger. I do not shrink from this responsibility — I welcome it. I do not believe that any of us would exchange places with any other people or any other generation. The energy, the faith, the devotion which we bring to this endeavor will light our country and all who serve it. And the glow from that fire can truly light the world. And so, my fellow Americans, ask not what your country can do for you; ask what you can do for your country. My fellow citizens of the world, ask not what America will do for you, but what together we can do for the freedom of man. Finally, whether you are citizens of America or citizens of the world, ask of us here the same high standards of strength and sacrifice which we ask of you. With a good conscience our only sure reward, with history the final judge of our deeds, let us go forth to lead the land we love, asking His blessing and His help, but knowing that here on earth God's work must truly be our own." # Tokenize the words all_words = speech_text.lower().split() # Create a frequency distribution freq = nltk.FreqDist(all_words) # Show the top 10 words in the list, with counts freq.items()[:10] Out[5]: [('the', 86), ('of', 66), ('to', 42), ('and', 40), ('we', 30), ('a', 29), ('in', 24), ('our', 21), ('not', 19), ('that', 19)] # Show the top 10 keys in the frequency dictionary freq.keys()[:10] Out[6]: ['the', 'of', 'to', 'and', 'we', 'a', 'in', 'our', 'not', 'that'] # Those frequent words aren't very interesting... let's strip common words from nltk.corpus import stopwords stop_words = set(stopwords.words('english')) clean_words = [w for w in all_words if not w in stop_words] freq_clean = nltk.FreqDist(clean_words) # This is a little more interesting freq_clean.items()[1:10] [('let', 16), ('us', 11), ('new', 7), ('sides', 7), ('pledge', 6), ('ask', 5), ('shall', 5), ('always', 4), ('call', 4)]
如果需要，NLTK将允许您使用文本进行各种其他有趣的分析。 下面是一个简单的例子，你将如何find在文中出现3次以上的前10名的前两名：
bigram_measures = nltk.collocations.BigramAssocMeasures() bigram_finder = nltk.collocations.BigramCollocationFinder.from_words(all_words) bigram_finder.apply_freq_filter(3) bigram_finder.nbest(bigram_measures.pmi, 10) Out[28]: [('my', 'fellow'), ('both', 'sides'), ('can', 'do'), ('dare', 'not'), ('let', 'us'), ('we', 'dare'), ('do', 'for'), ('let', 'both'), ('we', 'shall'), ('a', 'call')]
有关更多信息和示例，请参阅NLTK文档 ，例如，快速创build文本中最常用术语的阴谋。
不知道有这样一个任务的Counter对象。 这就是我当时的做法，类似于你的方法。 您可以对同一个词典的表示进行sorting。
#Takes a list and returns a descending sorted dict of words and their counts def countWords(a_list): words = {} for i in range(len(a_list)): item = a_list[i] count = a_list.count(item) words[item] = count return sorted(words.items(), key = lambda item: item[1], reverse=True)
一个例子：
>>>countWords("the quick red fox jumped over the lazy brown dog".split()) [('the', 2), ('brown', 1), ('lazy', 1), ('jumped', 1), ('over', 1), ('fox', 1), ('dog', 1), ('quick', 1), ('red', 1)]
我几天前写了一个类似的程序。 程序使用两个参数：filename（必需）和N（可选）
from collections import Counter import re import sys if sys.version_info <(2,7): Sys.exit("Must use Python 2.7 or greater") if len(sys.argv)<2: sys.exit('Usage: python %s filename N'%sys.argv[0]) n=0 if len(sys.argv)>2: try: n=int(sys.argv[2]) if n<=0: raise ValueError except ValueError: sys.exit("Invalid value for N: %s.\nN must be an integer greater than 0"%sys.argv[2]) filename=sys.argv[1] try: with open(filename,"r") as input_text: wordcounter=Counter() for line in input_text: wordcounter.update(re.findall("\w+",line.lower())) if n==0: n=len(wordcounter) for word, frequency in wordcounter.most_common(n): print("%s %d" % (word, frequency)) except IOError: sys.exit("Cannot open file: %s"% filename)
