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Replace all occurrences of one substring with another substring

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Python’s str type also has a method for replacing occurences of one sub-string with another sub-string in a given string. For more demanding cases, one can use re.sub.

str.replace(old, new[, count]):

str.replace takes two arguments old and new containing the old sub-string which is to be replaced by the new sub-string. The optional argument count specifies the number of replacements to be made:

For example, in order to replace 'foo' with 'spam' in the following string, we can call str.replace with old = 'foo' and new = 'spam': 

>>> "Make sure to foo your sentence.".replace('foo', 'spam')
"Make sure to spam your sentence."

If the given string contains multiple examples that match the old argument, all occurrences are replaced with the value supplied in new: 

>>> "It can foo multiple examples of foo if you want.".replace('foo', 'spam')
"It can spam multiple examples of spam if you want."

unless, of course, we supply a value for count. In this case count occurrences are going to get replaced: 

>>> """It can foo multiple examples of foo if you want, \
... or you can limit the foo with the third argument.""".replace('foo', 'spam', 1)
'It can spam multiple examples of foo if you want, or you can limit the foo with the third argument.'
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String Methods:
* String Methods
* Changing the capitalization of a string
* str.translate Translating characters in a string
* str.format and f-strings Format values into a string
* String modules useful constants
* Replace all occurrences of one substring with another substring
* Reversing a string
* Testing what a string is composed of
* Split a string based on a delimiter into a list of strings
* Stripping unwanted leading/trailing characters from a string
* String Contains
* Join a list of strings into one string
* Counting number of times a substring appears in a string
* Case insensitive string comparisons
* Test the starting and ending characters of a string
* Justify strings
* Conversion between str or bytes data and unicode characters
Table Of Contents
0 Getting Started
1 List comprehension
2 Filter
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4 Functions
5 Decorators
6 Math module
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39 Incompatibilities moving from Python 2 to Python 3
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56 Creating Python packages
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63 Itertools Module
64 Recursion
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66 dis module
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68 pip PyPI Package Manager
69 locale module
70 Exceptions
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72 deque module
73 Distributing self-contained applications
74 Property Objects
75 Overloading
76 Debugging
77 Reading and Writing CSV
78 Dynamic code execution with exec and eval
79 PyInstaller - Distributing Python Code
80 Iterables and Iterators
81 Data Visualization
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83 args and kwargs
84 functools module
85 Garbage Collection
86 Indentation
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88 Pickle data serialization
89 urllib
90 Binary Data
91 Python and Excel
92 Idioms
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94 Difference between a module and a package
95 Data Serialization
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97 RabbitMQ using AMQPStorm
98 PostgreSQL
99 Descriptor
100 Common Pitfalls
101 Multiprocessing
102 Creating temporary files with tempfile
103 Working with ZIP files
104 Stack
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108 Deployment using conda
109 Logging
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111 os module
112 Comments and documentation
113 Database Access
114 Python HTTP Server
115 Alternatives to switch statement from other languages
116 List destructuring
117 Accessing Python source code and bytecode
118 Mixins
119 Attribute Access
120 ArcPy
121 Python Anti-Patterns
122 Plugin and Extension Classes
123 Websockets
124 Immutable data types
125 String representations of class
126 Arrays
127 Operator Precedence
128 Polymorphism
129 Alternative Python implementations
130 List Comprehensions
131 Web Server Gateway Intrerface WSGI
132 2to3 tool
133 Abstract Syntax Tree
134 Abstract Base Classes
135 Unicode
136 ssh in Python
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138 Neo4j
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143 Testing with py.test
144 Date Formatting
145 heapq
146 tkinter
147 CLI subcommands
148 Defining functions with list arguments
149 SQLite3 module
150 Persistence with pickle
151 Connecting to SQL Server
152 Design Patterns
153 Multidimensional arrays
154 Audio
155 pyglet
156 queue module
157 ijson
158 webbrowser module
159 base64 module
160 Flask
161 Groupby
162 Sockets and Message Encryption / Decryption
163 pygame
164 Input Subset and Output External Data Files using Pandas
165 hashlib
166 Gzip
167 ctypes
168 Creating a Windows Service
169 Mutable vs. Immutable
170 configparser
171 Common Exceptions
172 Optical Character Recognition OCR
173 Python Data Types
174 Partial functions
175 Generating graphs
176 Unzipping Files
177 Functional Programming
178 Python Virtual Environment - virtualenv
179 sys module
180 virtual environment with virtualenvwrapper
181 virtualenvwrapper on Windows
182 Python Requests Post
183 Plotting with Matplotlib
184 Python Lex-Yacc
185 pyaudio
186 shelve
187 pip and PyPI Package Manager
188 Writing to CSV from String or List
189 Raise Custom Errors Exceptions
190 Using loops within functions
191 Contributors