8.12.2 Replacing Substrings and Splitting Strings

• sub function replaces patterns in a string
• split function breaks a string into pieces, based on patterns

Function sub—Replacing Patterns

• sub function replaces all occurrences of a pattern with the replacement text you specify

import re

re.sub(r'\t', ', ', '1\t2\t3\t4')

• Three required arguments:
  • the pattern to match (the tab character '\t')
  • the replacement text (', ') and
  • the string to be searched ('1\t2\t3\t4')
• Keyword argument count can be used to specify the maximum number of replacements

re.sub(r'\t', ', ', '1\t2\t3\t4', count=2)

Function split

• split function tokenizes a string, using a regular expression to specify the delimiter
• Returns a list of strings

re.split(r',\s*', '1,  2,  3,4,    5,6,7,8')

• Keyword argument maxsplit specifies maximum number of splits

re.split(r',\s*', '1,  2,  3,4,    5,6,7,8', maxsplit=3)

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