Python - 從字串中移除不需要的字元

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Python 是一種非常常用的程式，用於各種目的，例如 Web 開發、資料科學、機器學習，以及執行各種自動化流程。在任何應用領域工作時，我們都必須處理一個共同的東西，即字串。因此，在本文中，我們將學習如何從字串中移除不需要的字元。

替換

在這種方法中，我們只需指定不需要的元素，然後移除該元素，並在字串中留下一個空位。我們可以透過以下示例更好地理解它

示例

def unwanted_string_words(data, sentence):  #Input is provided
    for sent in sentence:   #Check different characters in string
        data = data.replace(sent, '')   #Remove unwanted characters from string
    return data 

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string)  

輸出

以上程式碼的輸出如下所示

Hi My Name Is John 

re 模組

在這種方法中，我們將使用正則表示式模組從字串中移除字元。我們可以從以下示例中瞭解其用法

示例

import re   # Do not forget to import the re module or else error might occur

def unwanted_string_words(data, sentence):   # The input is provided
    pattern = "[" + re.escape("".join(sentence)) + "]"  #We will join all the characters using re.escape
    return re.sub(pattern, "", data)   # We will then use re.sub to remove the unwanted characters

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string)  

輸出

以上示例的輸出如下所示

Hi My Name Is John 

列表推導式

透過這種方法，我們將建立一個僅包含所需字元的新列表，在從原始字串中移除所有不需要的字元之後。我們可以透過以下示例清楚地瞭解它

示例

def unwanted_string_words(data, sentence):   #The input is provided
   return ''.join([sent for sent in data if sent not in sentence])   # All the characters in the string are checked and the characters which are not to be removed sre moved to a new list and some characters are removed.

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string)  

輸出

以上示例的輸出如下所示

Hi My Name Is John 

translate 方法

這是一種非常有用的方法，可以從字典列表中移除字元。要移除的字元在轉換表中指定，並相應地移除。以下是如何使用 translate 方法移除字元的示例

示例

def unwanted_string_words(data, sentence):  #The input of string is provided
    translation_table_characters = str.maketrans('', '', ''.join(sentence))    # With the help pf str.maketrans a translation table is made and the characters to be removed are specified     
    return data.translate(translation_table_characters)  #The str.translate is used to remove the characters and provide an empty space

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string) 

輸出

以上示例的輸出如下所示

Hi My Name Is John 

filter 函式

顧名思義，在這種方法中，我們將指定一些過濾器以從我們的字串中移除一些字元。這是從字串中移除字元的最簡單方法之一。我們可以透過以下示例更清楚地瞭解它

示例

def unwanted_string_words(data, sentence):  # The input of string is given
    unwanted_string_words = filter(lambda sent: sent not in sentence, data)  #Filter will check all the characters of the string
    # Lambda will be used to look for the unwanted characters in the whole string
    return ''.join(unwanted_string_words)  #After removing the unwanted characters, the remaining characters are moved to a new list 

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string) 

輸出

以上示例的輸出如下所示

Hi My Name Is John 

列表 & 連線

在這種方法中，整個字串被轉換為字元，然後檢查所有字元，並從列表中移除所有不需要的字元。我們可以透過以下示例更好地理解它

示例

def unwanted_string_words(data, sentence):  # The input of string is provided 
    unwanted_string_words = [sent for sent in data if sent not in sentence]  # List comprehension will be used to check each characters and the unwanted ones will be removed
    return ''.join(unwanted_string_words)  #The remaining characters will be joined to form a string

# Example
whole_string = "Hi! My Name Is, John"
to_be_removed = "!,"
final_string =unwanted_string_words(whole_string, to_be_removed)
print(final_string) 

輸出

以上示例的輸出如下所示

Hi My Name Is John 

結論

程式中存在的字串的編輯是程式設計師遵循的常見過程。因此，瞭解以上所有方法對於成為一名高效快捷的程式設計師至關重要。可以參考本文了解許多從字串中移除字元的不同方法。