Python Learning Note 5-closing and builder

>>> Import re>>> re.search (' [ABC] ', ' Mark ') <_sre. Sre_match object; Span= (1, 2), match= ' a ' >>>> re.sub (' [ABC] ', ' o ', ' Mark ') ' Mork ' >>> re.sub (' [ABC] ', ' o ', ' carp ') ' Oorp '

Note:

[ABC]--match any one of the characters in the A,b,c

[^ABC]--match any character except A,b,c

>>> Import re>>> re.search (' [^aeiou]y$ ', ' vancancy ') <_sre. Sre_match object; Span= (6, 8), match= ' Cy ' >>>> re.sub (' y$ ', ' ies ', ' vacancy ') ' Vacancies ' >>> re.sub (' ([^aeiou]) y$ ', R ' \1ies ', ' vacancy ') ' vacancies '

Note:

\1--means that the first matching grouping is placed in that location. If you have more than one grouping, you can use \2, \3, and so on.

List of functions:

A. The technique of using external parameter values in dynamic functions is called closure.

Import Redef build_match_and_apply_functions (pattern,search,replace):d ef matches_rule (Word): Return Re.search ( Pattern,word) def apply_rule (word): return re.sub (Search,replace,word) return (Matches_rule,apply_rule)

B.

>>> patterns = (' [sxz]$ ', ' $ ', ' es '), (' [aeioudgkprt]h$ ', ' $ ', ' es '), (' (qu|[ ^aeiou]) y$ ', ' y$ ', ' ies '), (' $ ', ' $ ', ' s ')) >>> rules = [Build_match_and_apply_functions (pattern, search, Replace) for (pattern, search, replace) in Patterns]>>> rules[(<function build_match_and_apply_functions. <locals>.matches_rule at 0x10384d510>, <function build_match_and_apply_functions.<locals>.apply_ Rule at 0x10384d598>), (<function build_match_and_apply_functions.<locals>.matches_rule at 0x10384d620 <function Build_match_and_apply_functions.<locals>.apply_rule at 0x10384d6a8>), (<function Build_match_and_apply_functions.<locals>.matches_rule at 0x10384d730>, <function build_match_and_apply _functions.<locals>.apply_rule at 0x10384d7b8>), (<function build_match_and_apply_functions.<locals >.matches_rule at 0x10384d840>, <function build_match_and_apply_functions.<locals>.apply_rule at 0x10384d8c8>)]>>>  

C. Matching pattern file

Import Redef build_match_and_apply_functions (pattern, search,replace):d EF matches_rule (Word): Return Re.search ( Pattern,word) def apply_rule (word): return re.sub (Search,replace,word) return (matches_rule,apply_rule) rules = []with Open (' plural4-rules.txt ', encoding = ' utf-8 ') as Pattern_file:for line in pattern_file:pattern,search,replace = Line.split (none,3) rules.append (Build_match_and_apply_functions (pattern,search,replace))

1) Open (): Opens the file and returns a file object.

2) ' with ': Creates a context: when the With statement ends, Python automatically closes the file, that is, the open is an unexpected occurrence.

3) Split (none,3): None indicates that any whitespace characters (spaces, tables, and so on) are delimited. 3 indicates that the remaining portion of the line is discarded three times for whitespace.

Generator:

>>> def make_counter (x):p rint (' entering Make_counter ') while True:yield xprint (' incrementing x ') x=x+1> >> counter = make_counter (2) >>> Counter<generator object Make_counter at 0x1038643f0>>>> Next (counter) entering make_counter2>>> next (counter) incrementing x3>>> next (counter) incrementing X4>>> Next (counter) incrementing X5

def fib (max): b = 0, 1while a < Max:yield AA, B = b, a+b>>> for n in fib ():p rint (n,end= ") 0 1 1 2 3 5 8 >>> List (FIB (200)) [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144

1) Pass a generator to the list () function, which will traverse the entire generator and return all generated values.

Python Learning Note 5-closing and builder