Day, module-basedir, OS, JSON module, Pickle, and regular module.

Iv. Regular,

RE module:Action: Object to: String,

Pre-Class Introduction:

Example One,

s='dsdsadsadadsalexdsds'
S.find (' Alex ')

How to find the inside of the string Alex;? Learn how to use the past: Find, split, replace. But the method of string built-in is very limited, and can only achieve exact match.

If you want to find: What's the need to start with a**? Can not be achieved. Fuzzy matching is used to achieve fuzzy matching.

Example two, fuzzy matching

# in the text there is a bunch of ID 4504231989347382822110423198934738282211042319923473828221104231995347382822 ...  # demand: Find people from Beijing after 1990 years of origin

^110......1990+*

Find a bunch of numbers inside a string:

The regular is essentially a small, highly specialized programming language. (python) is embedded in Python and is implemented through the RE module. The regular expression pattern is compiled into a sequence of bytecode, which is then executed by a matching engine written in C.

Character matching: (normal character, metacharacters)

Ordinary characters: Most characters and letters will match themselves

　Import Re Print (Re.findall ('Alex','dsfjdsfldsjfdalexdsds')) >>>['Alex']

Metacharacters:. ^ $ * +? {} [] | () \

Character Explanation:

1?? wildcard character '. '

Import Re Print (Re.findall ('A.. x','dsfjdsfldsjfdalexdsds'))>>>['  Alex']

2??、 Sharp Horn:^ with what begins. Match at the beginning of the string. If the match meets the requirements, the matching succeeds.

Import Re Print (Re.findall ('^d. J','dsfjdsfldsjfdalexdsds'))>>>['  dsfj']

3??、 The $ symbol ends with what,

Import Re Print (Re.findall ('d.. S $','dsfjdsfldsjfdalexdsds'))>>>>[ ' DSDS ']

Repeating symbols:

4??、 * (0,∞) d* to match the characters next to each other in Infinity → greedy matches,

ImportRePrint(Re.findall ('d*','Dsfjdsflddddddddddsjfdalexdsds'))>>>['D',"',"',"','D',"',"',"','dddddddddd',"',"',"','D',"',"',"',"','D',"','D',"',"']

Import Re Print (Re.findall ('^d*','dsfjdsflddddddddddsjfdalexdsds')) >>['d']

???、 + match [1,∞] least match one character trailing plus one? The number becomes an inert match.

ImportRePrint(Re.findall ('alex*','Dsfjdsfalesjfdsds'))ImportRePrint(Re.findall ('alex+','Dsfjdsflalesjfdsds'))>>>['Ale'][]

6??、? [0,1]

Import Re Print (Re.findall ('Alex? ','dsfjdsflalexxxsjfdsds'))>>>['  Alex']

7??、 {0,}=*:0} to infinity, {1,}=+: "1,+00", {0,1}=? , {6} repeated 6 times

Import Re Print (Re.findall ('alex{6}','dsfjdsflalexxxsjfdsds')) >>>[]

Add: Add:? It becomes an inert match, with the smallest to find a match.

ImportRePrint(Re.findall ('alex+?','Dsfjdsflalexxxsjfdsds'))ImportRePrint(Re.findall ('alex*?','Dsfjdsflalexxxsjfdsds'))>>>>['Alex']['Ale']

8??、 []: Character set. Any symbol placed inside is a normal symbol that matches one of the inside

Apart from

"A-Z" range, A to Z

Import Re Print (Re.findall ('x[a-z]*','xypsssdsdsdsdssxzp')) >>>['xypsssdsdsdsdssxzp']

"^a-z" meaning: non-matching non-A to Z letters

ImportRePrint(Re.findall ('www. [Oldboy Baidu]','Www.baid'))ImportRePrint(Re.findall ('X[yz]','Xyssssxz'))ImportRePrint(Re.findall ('x[yz]p','Xypssssxzp'))>>>['www.b']['XY','XZ']['Xyp','Xzp']

9??、

Day, module-basedir, OS, JSON module, Pickle, and regular module.