Python Replace ExampleUse the replace method to change a substring in a string into another substring.
A string cannot be changed in-place. We cannot assign characters. Instead we use the replace method to create a new string.Strings
With this method, we specify a substring that we want to replace, and another we want to replace it with. We can use an optional second argument.
Let us begin with this simple example. Replace accepts two substring arguments: the "before" and "after" parts that are replaced.
And: The third argument is optional. It is a count. It indicates the maximum number of instances to replace.
Tip: Replace only handles substrings, not characters. If you need to replace many single characters, please consider the translate method.Translate
Python program that uses replace
value = "aabc"
# Replace a substring with another.
result = value.replace("bc", "yz")
# Replace the first occurrence with a substring.
result = value.replace("a", "x", 1)
The third argument to replace() is optional. If we specify it, the replace method replaces that number of occurrences—this is a count argument.
Here: We have a string that says "cat cat cat" and we replace all occurrences, 0 occurrences, and 1 and 2 occurrences.
Python program that uses replace, count argument
before = "cat cat cat"
# Replace all occurrences.
after = before.replace("cat", "bird")
# Replace zero occurrences.
# ... This makes no sense.
after = before.replace("cat", "bird", 0)
# Replace 1 occurrence.
after = before.replace("cat", "bird", 1)
# Replace first 2 occurrences.
after = before.replace("cat", "bird", 2)
cat cat cat
bird bird bird
cat cat cat
bird cat cat
bird bird cat
Replace() is needed to change a part of string to a new string. If the index of the match is known, we could use two slices and then construct a new string with concatenation.Substring
A summary. With replace() we copy a string. The original is not changed. The copied string has the specified number of substrings replaced with a new substring (if found).
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