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嘿伙计们,我正在尝试通过运行以下程序来运行我的程序...

from hashtable import *


def word_count( hTable, filename ):
    """
        Record the frequency of all words in the named file in the hashtable.
        word_count : HashTable String -> HashTable
    """

    # Read the words of the text file into the word count table.
    fd = open( filename )
    for line in fd:
        for word in line.split():
            # using a regular expression argument to strip(),
            # strip out punctuation and convert token to lower-case.
            word = word.strip(",.\"\';:-!?").lower()
            if contains( hTable, word ):
                count = get( hTable, word )
                put( hTable, word, count + 1 )
            else:
                put( hTable, word, 1 )

    fd.close()          # closing the file is a 'good practice'.
    return hTable

def printSummary( theTable ):
    """
    printSummary prints a summary of information about the hash table contents.
    printSummary : HashTable -> NoneType
    """

    # Display the entire table!
    print( "Unique words:", theTable.size )

    # Find the most common word in the text file.
    total = 0
    maxWord = ""
    maxCount = 0
    for key in keys( theTable ):
        thisCount = get( theTable, key )
        total += thisCount
        if thisCount > maxCount:
            maxCount = thisCount
            maxWord = key

    print( "There are " + str( len( keys( theTable ) ) ) + " words." )
    print( "Total words:", total )
    print( '"' + maxWord + "\" appeared ", str( maxCount ),
          " times, more than any other word." )

def printTable( hTable ):
    """
        Print the contents of the given hash table.
        Each key/value pair is displayed in parentheses, tuple-style.
        All pairs appear on a single line.
        printTable : HashTable -> NoneType
    """
    print( "Word Count Data ---------------" )
    lcount = 0
    ltext = 0
    for key in keys( hTable ):
        # print( "(" + key + "," + str( get( hTable, key ) ) + ")", end=" " )
        txt = "(" + key + "," + str( get( hTable, key ) ) + ")"
        ltext += len( txt )
        if ltext > 51:
            print( txt )
            ltext = 0
        else:
            print( txt, end=" " )
    print()

def main():
    capacity = int( input( "Enter capacity (-1 for default): " ) )
    if capacity < 0:
        hTable = HashTable()
    else:
        hTable = HashTable( capacity )
    filename = input( "Enter filename: " )

    wordTable = word_count( hTable, filename )
    printSummary( wordTable )

    while True:

        print( "Commands: k[ey] <word> f[ind] <word> q[uit] ? ", end=" " )
        response = input( ":- " )   # the displayed prompt
        query = response.split()

        if len( response ) == 0 or not response[0] in "fkq": 
            print( response + " invalid. Please enter a command and a word." )
            response = ""
            continue

        if query[0] == "k":
            print( "( " + query[1] + " in text ) is " \
                 + str( contains( wordTable, query[1] ) ) + "." )

        if query[0] == "f":
            if contains( wordTable, query[1] ):
                print( query[1] + " appears " \
                     + str( get( wordTable, query[1] ) ) + " times." )
            else:
                print( query[1] + " in not in the text." )

        if query[0] == "q":
            break
    # 
    answer = input( "Do you want to see the entire table?(y/n) " )
    if answer != "y":
        return
    printTable( wordTable )

# run the main program
main()

该程序使用...

class HashTable( ):
    """
       The HashTable data structure contains a collection of values
       where each value is located by a hashable key.
       No two values may have the same key, but more than one
       key may have the same value.
    """

    __slots__ = ( "table", "size" )


def mkHashTable(capacity=100):
  aHashTable = HashTable()
  aHashTable.table = [[] for _ in range(capacity)]
  aHashTable.size = 0
  return aHashTable

def HashTableToStr(hashtable):
  result = ""
  for i in range( len( hashtable.table ) ):
      if i != None:
          result += str( i ) + ": "
          result += EntryToStr( hashtable.table[i] ) + "\n"
  return result


class _Entry( ):
    """
       A class used to hold key/value pairs.
    """

    __slots__ = ( "key", "value" )


def EntryToStr(entry):
  """
       return the string representation of the entry.
  """
  return "(" + str( entry.key ) + ", " + str( entry.value ) + ")" 

def mkEntry(key, value):
  aEntry = _Entry();
  aEntry.key = key;
  aEntry.value = value;
  return aEntry;


def hash_function( val, n ):
    """
       Compute a hash of the val string that is in [0 ... n).
    """
    hashcode = hash( val ) % n
    # hashcode = 0
    # hashcode = len(val) % n
    return hashcode

def keys( hTable ):
    """
       Return a list of keys in the given hashTable.
    """
    result = []
    for entry in hTable.table:
        if entry != []:
            for item in entry:
                if item.key not in results:
                    result.append( entry.key )
    return result

def contains( hTable, key ):
    """
       Return True iff hTable has an entry with the given key.
    """
    index = hash_function( key, len( hTable.table ) )
    startIndex = index # We must make sure we don't go in circles.
    while hTable.table[ index ] != None and hTable.table[ index ].key != key:
        index = ( index + 1 ) % len( hTable.table )
        if index == startIndex:
            return False
    return hTable.table[ index ] != None

def put( hTable, key, value ):
    """
       Using the given hash table, set the given key to the
       given value. If the key already exists, the given value
       will replace the previous one already in the table.
       If the table is full, an Exception is raised.
    """
    hashCode = hash(key)
    loc = hashCode % len(hTable.table)
    if hTable.table[loc] == []:
        hTable.table[loc] = HashTable._Entry(key, value)
        hTable.size += 1
    else:
        hTable.table[loc].value = value

def get( hTable, key ):
    """
       Return the value associated with the given key in
       the given hash table.
       Precondition: contains(hTable, key)
    """
    hashCode = hash(key)
    loc = hashCode % len(hTable.table)
    for entry in hTable.table[loc]:
        if entry.key == key:
            return entry.value

我收到以下错误...

Enter capacity (-1 for default): -1
Enter filename: words.txt
Traceback (most recent call last):
  File "/Users/sps329/Desktop/word_count.py", line 126, in <module>
    main()
  File "/Users/sps329/Desktop/word_count.py", line 92, in main
    wordTable = word_count( hTable, filename )
  File "/Users/sps329/Desktop/word_count.py", line 29, in word_count
    if contains( hTable, word ):
  File "/Users/sps329/Desktop/hashtable.py", line 83, in contains
    index = hash_function( key, len( hTable.table ) )
AttributeError: table

我在程序中的目标是在哈希程序中实现链接并提出更好的哈希函数。

4

1 回答 1

3

您构造HashTable实例的代码main()不正确。您正在调用HashTable构造函数,而不是mkHashTable实际将table属性放入HashTable实例中的工厂函数。如果没有table初始化属性,您将得到您描述的异常。

请注意,您的hashtable模块的设计非常糟糕。该类HashTable__init__方法确实应该重新设计以执行该mkHashTable操作。让构造函数返回一个非函数对象是愚蠢的。

它不是唯一糟糕的设计。中的几乎所有函数都hashtable.py应该是HashTable(或_Entry)类的方法。如果它们以特殊的方式命名,它们中的一些可以得到 Python 的特殊支持:contains应该是一个__contains__方法(让你用 测试word in table)并且HashTableToStr应该是一个__str__方法(所以你可以用 打印print(table))。

于 2013-10-29T03:52:22.663 回答