An example Analysis of the function re.sub bytes string which is easy to be encountered in python data cleaning

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Re.sub

Function, a more powerful replacement function than replace, replacing the module on regular expression matching with repl

Re.sub (pattern, repl, string, count=0, flags=0)

Returns the string qualified by the leftmost regular expression that is replaced by repl. If the regular expression does not match, the string is not modified.

\ n is converted to a single newline character

\ r is converted to a carriage return, and so forth. Unknown escapes such as\ j are left alone. If it is followed by the number such as\ 6, replace the sixth set of strings, group 6 in the pattern. For example:

> re.sub (r'def\ s + ([a murzAmurz ZZ] [a-zA-Z_0-9] *)\ s *\ (\ s *\):',. R'static PyObject*\ npy_\ 1 (void)\ n {',... 'def myfunc (): 'static PyObject*\ npy_myfunc (void)\ n {'

If repl is a function, a call occurs for each pattern that does not overlap. This function takes a single matching object parameter and returns a replacement string. For example:

> def dashrepl (matchobj):... If matchobj.group (0) ='-': return''... Else: return'-'> > re.sub ('- {1 sAND 2}', dashrepl, 'pro----gram-files')' pro--gram files' > re.sub (r'\ sAND\ s,'&', 'Baked Beans And Spam', flags=re.IGNORECASE)' Baked Beans & Spam'

The template can be a string or a RE object

Count is the maximum number of replacements, which is a non-negative integer. If omitted or 0 is taken, the full file will be matched and replaced.

Class bytes ([source [, encoding [, errors])

Returns a new array object that cannot be modified to array elements. Value range of each element: 0