我需要My Dictionary程序中的帮助

Question

def createdictionary():
    mydictionary = dict()
    mydictionary['Computer']='Computer is an electronic machine.'
    mydictionary['RAM']='Random Access Memory'
    return mydictionary

def insert(dictionary):
    print("Enter the keyword you want to insert in the dictionary: ")
    key=input()
    print("Enter its meaning")
    meaning=input()
    dictionary[key]=meaning
    f = open('dict_bckup.txt','a')
    f.write(key)
    f.write('=')
    f.write(meaning)
    f.write(';\n')
    f.close()
    print("Do you want to insert again? y/n")
    ans=input()
    if ( ans == 'y' or ans=='Y' ):
        insert(dictionary)

def display(dictionary):
    print("The contents of the dictionary are : ")
    f = open('dict_bckup.txt','r')
    print(f.read())
    f.close()

def update(dictionary):
    print("Enter the word whose meaning you want to update")
    key=input()
    #i want to edit the meaning of the key in the text file
    f = open('dict_bckup.txt','w')
    if key in dictionary:
        print(dictionary[key])
        print("Enter its new meaning: ")
        new=input()
        dictionary[key]=new
    else:
        print("Word not found! ")
    print("Do you want to update again? y/n")
    ans=input()
    if (ans=='y' or ans=='Y'):
        update(dictionary)

def search(dictionary):
    print("Enter the word you want to search: " )
    word=input()
    if word in dictionary:
        print(dictionary[word])

else:
    print("Word not found! ")
print("Do you want to search again? y/n")
ans=input()
if(ans=='y' or ans=='Y'):
    search(dictionary)


def delete(dictionary):
    print("Enter the word you want to delete: ")
    word=input()
    if word in dictionary:
        del dictionary[word]
        print(dictionary)
    else:
        print("Word not found!")

    print("Do you want to delete again? y/n ")
    ans=input()
    if ( ans == 'y' or ans == 'Y' ):
        delete(dictionary)

def sort(dictionary):
    for key in sorted(dictionary):
        print(" %s: %s "%(key,(dictionary[key])))


def main():
    dictionary=createdictionary()
    while True:

        print("""             Menu
            1)Insert
            2)Delete
            3)Display Whole Dictionary
            4)Search
            5)Update Meaning
            6)Sort
            7)Exit
          Enter the number to select the coressponding field """)

        ch=int(input())

        if(ch==1):
            insert(dictionary)

        if(ch==2):
            delete(dictionary)

        if(ch==3):
            display(dictionary)

        if(ch==4):
            search(dictionary)

        if(ch==5):
            update(dictionary)

        if(ch==6):
            sort(dictionary)

        if(ch==7):                                        
            break


main()

我是python的新手。我已经尝试了好几天才能得到这个。但仍未找到解决方案。事情是我最初做了一个简单的字典程序，存储单词及其含义。然后我想我应该永久存储这些词。我有点试图将文字存储在文本文件中并显示它。但我没有得到如何搜索文本文件中的单词。并且假设我找到了这个词，我想更新它的含义。那我该怎么做呢。因为如果我使用'w'重写整个文本文件，它将被重写。而且我应该如何删除它。我知道我在文件中插入文字的方式也是错误的。请帮我解决一下这个。

Answer 1

正如@Vaibhav Desai所提到的，你可以定期写整本字典。例如，考虑编写序列化对象的pickle module：

import pickle

class MyDict(object):
    def __init__(self, f, **kwargs):
        self.f = f
        try:
            # Try to read saved dictionary
            with open(self.f, 'rb') as p:
                self.d = pickle.load(p)
        except:
            # Failure: recreating
            self.d = {}
        self.update(kwargs)

    def _writeback(self):
        "Write the entire dictionary to the disk"
        with open(self.f, 'wb') as p:
            pickle.dump(p, self.d)

    def update(self, d):
        self.d.update(d)
        self._writeback()

    def __setitem__(self, key, value):
        self.d[key] = value
        self._writeback()

    def __delitem__(self, key):
        del self.d[key]
        self._writeback()

    ...

每次进行修改时，这都会将整个字典重写到磁盘，这在某些情况下可能有意义，但可能不是最有效的。您还可以创建一个更加聪明的机制，定期调用_writeback，或者要求明确调用它。

正如其他人所建议的那样，如果您需要对字典进行大量写操作，那么最好使用sqlite3 module，将SQL表作为字典：

import sqlite3

class MyDict(object):
    def __init__(self, f, **kwargs):
        self.f = f
        try:
            with sqlite3.connect(self.f) as conn:
                conn.execute("CREATE TABLE dict (key text, value text)")
        except:
            # Table already exists
            pass

    def __setitem__(self, key, value):
        with sqlite3.connect(self.f) as conn:
            conn.execute('INSERT INTO dict VALUES (?, ?)', str(key), str(value))

    def __delitem__(self, key):
        with sqlite3.connect(self.f) as conn:
            conn.execute('DELETE FROM dict WHERE key=?', str(key))

    def __getitem__(self, key):
        with sqlite3.connect(self.f) as conn:
            key, value = conn.execute('SELECT key, value FROM dict WHERE key=?', str(key))
            return value

    ...

这只是一个例子，你可以保持连接打开并要求它显式关闭，或排队你的查询...但它应该让你大致了解如何将数据保存到磁盘。

通常，Python文档的Data Persistence部分可以帮助您找到最适合您问题的模块。

Answer 2

你是对的，将这些值存储在一个简单的文本文件中是个坏主意。如果要更新一个单词，则必须重写整个文件。而对于搜索单个单词，您最终可能会搜索文件中的每个单词。

有一些专门为字典设计的数据结构（例如，Trie树），但假设你的字典不是很大，你可以使用sqlite数据库。 Python有sqlite3库。查看documentation了解详情。

Answer 3

首先，每次在字典中发生更新或插入时写入磁盘都是一个非常糟糕的主意 - 您的程序只会耗费太多的I / O.因此，更简单的方法是将键值对存储在字典中，并在程序退出时或以某个固定的时间间隔将其保存到磁盘。

此外，如果您不热衷于以人类可读的形式（例如纯文本文件）将数据存储在磁盘上;您可以考虑使用内置的pickle模块，如here所示，将数据保存到定义良好的磁盘位置。因此，在程序启动期间，您可以从这个定义明确的位置读取并将数据“解开”回到字典对象中。通过这种方式，您可以单独使用字典对象，甚至可以轻松完成查找项目或删除项目等操作。请参阅以下解决您的要求的脚本。我已经使用 pickle 模块来持久保存到文件中，您可能希望将其转储到文本文件中并作为单独的练习从中读取。此外，我还没有使用后缀 2 来介绍我的功能，例如 insert2 ，以便您可以将您的功能与我的功能进行比较并了解差异：

另一件事 - 你的程序中有错误;你应该使用raw_input（）来读入用户输入而不是输入（）

import pickle
import os

def createdictionary():
    mydictionary = dict()
    mydictionary['Computer']='Computer is an electronic machine.'
    mydictionary['RAM']='Random Access Memory'
    return mydictionary

#create a dictionary from a dump file if one exists. Else create a new one in memory.    
def createdictionary2():

    if os.path.exists('dict.p'):
        mydictionary = pickle.load(open('dict.p', 'rb'))
        return mydictionary

    mydictionary = dict()
    mydictionary['Computer']='Computer is an electronic machine.'
    mydictionary['RAM']='Random Access Memory'
    return mydictionary

def insert(dictionary):
    print("Enter the keyword you want to insert in the dictionary: ")
    key=raw_input()
    print("Enter its meaning")
    meaning=raw_input()
    dictionary[key]=meaning
    f = open('dict_bckup.txt','a')
    f.write(key)
    f.write('=')
    f.write(meaning)
    f.write(';\n')
    f.close()
    print("Do you want to insert again? y/n")
    ans=raw_input()
    if ( ans == 'y' or ans=='Y' ):
        insert(dictionary)

#custom method that simply updates the in-memory dictionary
def insert2(dictionary):
    print("Enter the keyword you want to insert in the dictionary: ")
    key=raw_input()
    print("Enter its meaning")
    meaning=raw_input()
    dictionary[key]=meaning

    print("Do you want to insert again? y/n")
    ans=raw_input()
    if ( ans == 'y' or ans=='Y' ):
        insert(dictionary)



def display(dictionary):
    print("The contents of the dictionary are : ")
    f = open('dict_bckup.txt','r')
    print(f.read())
    f.close()

#custom display function - display the in-mmeory dictionary
def display2(dictionary):
    print("The contents of the dictionary are : ")
    for key in dictionary.keys():
        print key + '=' + dictionary[key] 

def update(dictionary):
    print("Enter the word whose meaning you want to update")
    key=input()
    #i want to edit the meaning of the key in the text file
    f = open('dict_bckup.txt','w')
    if key in dictionary:
        print(dictionary[key])
        print("Enter its new meaning: ")
        new=raw_input()
        dictionary[key]=new
    else:
        print("Word not found! ")
    print("Do you want to update again? y/n")
    ans=input()
    if (ans=='y' or ans=='Y'):
        update(dictionary)

#custom method that performs update of an in-memory dictionary        
def update2(dictionary):
    print("Enter the word whose meaning you want to update")
    key=input()
    #i want to edit the meaning of the key in the text file

    if key in dictionary:
        print(dictionary[key])
        print("Enter its new meaning: ")
        new=raw_input()
        dictionary[key]=new
    else:
        print("Word not found! ")
    print("Do you want to update again? y/n")
    ans=raw_input()
    if (ans=='y' or ans=='Y'):
        update(dictionary)

def search(dictionary):
    print("Enter the word you want to search: " )
    word=raw_input()
    if word in dictionary:
        print(dictionary[word])

    else:
        print("Word not found! ")
    print("Do you want to search again? y/n")
    ans=raw_input()
    if(ans=='y' or ans=='Y'):
        search(dictionary)


def delete(dictionary):
    print("Enter the word you want to delete: ")
    word=raw_input()
    if word in dictionary:
        del dictionary[word]
        print(dictionary)
    else:
        print("Word not found!")

    print("Do you want to delete again? y/n ")
    ans=raw_input()
    if ( ans == 'y' or ans == 'Y' ):
        delete(dictionary)

def sort(dictionary):
    for key in sorted(dictionary):
        print(" %s: %s "%(key,(dictionary[key])))

#this method will save the contents of the in-memory dictionary to a pickle file
#of course in case the data has to be saved to a simple text file, then we can do so too
def save(dictionary):
    #open the dictionary in 'w' mode, truncate if it already exists
    f = open('dict.p', 'wb')
    pickle.dump(dictionary, f)




def main():
    dictionary=createdictionary2() #call createdictionary2 instead of creatediction
    while True:

        print("""             Menu
            1)Insert
            2)Delete
            3)Display Whole Dictionary
            4)Search
            5)Update Meaning
            6)Sort
            7)Exit
          Enter the number to select the coressponding field """)

        ch=int(input())

        if(ch==1):
            insert2(dictionary)  #call insert2 instead of insert

        if(ch==2):
            delete(dictionary)

        if(ch==3):
            display2(dictionary) #call display2 instead of display

        if(ch==4):
            search(dictionary)

        if(ch==5):
            update2(dictionary) #call update2 instead of update

        if(ch==6):
            sort(dictionary)

        if(ch==7):                                        
            #save the dictionary before exit
            save(dictionary);
            break


main()