import re
help(re)
Help on module re:
NAME
re - Support for regular expressions (RE).
FILE
/Users/Matias/miniconda2/lib/python2.7/re.py
MODULE DOCS
http://docs.python.org/library/re
DESCRIPTION
This module provides regular expression matching operations similar to
those found in Perl. It supports both 8-bit and Unicode strings; both
the pattern and the strings being processed can contain null bytes and
characters outside the US ASCII range.
Regular expressions can contain both special and ordinary characters.
Most ordinary characters, like "A", "a", or "0", are the simplest
regular expressions; they simply match themselves. You can
concatenate ordinary characters, so last matches the string 'last'.
The special characters are:
"." Matches any character except a newline.
"^" Matches the start of the string.
"$" Matches the end of the string or just before the newline at
the end of the string.
"*" Matches 0 or more (greedy) repetitions of the preceding RE.
Greedy means that it will match as many repetitions as possible.
"+" Matches 1 or more (greedy) repetitions of the preceding RE.
"?" Matches 0 or 1 (greedy) of the preceding RE.
*?,+?,?? Non-greedy versions of the previous three special characters.
{m,n} Matches from m to n repetitions of the preceding RE.
{m,n}? Non-greedy version of the above.
"\\" Either escapes special characters or signals a special sequence.
[] Indicates a set of characters.
A "^" as the first character indicates a complementing set.
"|" A|B, creates an RE that will match either A or B.
(...) Matches the RE inside the parentheses.
The contents can be retrieved or matched later in the string.
(?iLmsux) Set the I, L, M, S, U, or X flag for the RE (see below).
(?:...) Non-grouping version of regular parentheses.
(?P<name>...) The substring matched by the group is accessible by name.
(?P=name) Matches the text matched earlier by the group named name.
(?#...) A comment; ignored.
(?=...) Matches if ... matches next, but doesn't consume the string.
(?!...) Matches if ... doesn't match next.
(?<=...) Matches if preceded by ... (must be fixed length).
(?<!...) Matches if not preceded by ... (must be fixed length).
(?(id/name)yes|no) Matches yes pattern if the group with id/name matched,
the (optional) no pattern otherwise.
The special sequences consist of "\\" and a character from the list
below. If the ordinary character is not on the list, then the
resulting RE will match the second character.
\number Matches the contents of the group of the same number.
\A Matches only at the start of the string.
\Z Matches only at the end of the string.
\b Matches the empty string, but only at the start or end of a word.
\B Matches the empty string, but not at the start or end of a word.
\d Matches any decimal digit; equivalent to the set [0-9].
\D Matches any non-digit character; equivalent to the set [^0-9].
\s Matches any whitespace character; equivalent to [ \t\n\r\f\v].
\S Matches any non-whitespace character; equiv. to [^ \t\n\r\f\v].
\w Matches any alphanumeric character; equivalent to [a-zA-Z0-9_].
With LOCALE, it will match the set [0-9_] plus characters defined
as letters for the current locale.
\W Matches the complement of \w.
\\ Matches a literal backslash.
This module exports the following functions:
match Match a regular expression pattern to the beginning of a string.
search Search a string for the presence of a pattern.
sub Substitute occurrences of a pattern found in a string.
subn Same as sub, but also return the number of substitutions made.
split Split a string by the occurrences of a pattern.
findall Find all occurrences of a pattern in a string.
finditer Return an iterator yielding a match object for each match.
compile Compile a pattern into a RegexObject.
purge Clear the regular expression cache.
escape Backslash all non-alphanumerics in a string.
Some of the functions in this module takes flags as optional parameters:
I IGNORECASE Perform case-insensitive matching.
L LOCALE Make \w, \W, \b, \B, dependent on the current locale.
M MULTILINE "^" matches the beginning of lines (after a newline)
as well as the string.
"$" matches the end of lines (before a newline) as well
as the end of the string.
S DOTALL "." matches any character at all, including the newline.
X VERBOSE Ignore whitespace and comments for nicer looking RE's.
U UNICODE Make \w, \W, \b, \B, dependent on the Unicode locale.
This module also defines an exception 'error'.
CLASSES
exceptions.Exception(exceptions.BaseException)
sre_constants.error
class error(exceptions.Exception)
| Method resolution order:
| error
| exceptions.Exception
| exceptions.BaseException
| __builtin__.object
|
| Data descriptors defined here:
|
| __weakref__
| list of weak references to the object (if defined)
|
| ----------------------------------------------------------------------
| Methods inherited from exceptions.Exception:
|
| __init__(...)
| x.__init__(...) initializes x; see help(type(x)) for signature
|
| ----------------------------------------------------------------------
| Data and other attributes inherited from exceptions.Exception:
|
| __new__ = <built-in method __new__ of type object>
| T.__new__(S, ...) -> a new object with type S, a subtype of T
|
| ----------------------------------------------------------------------
| Methods inherited from exceptions.BaseException:
|
| __delattr__(...)
| x.__delattr__('name') <==> del x.name
|
| __getattribute__(...)
| x.__getattribute__('name') <==> x.name
|
| __getitem__(...)
| x.__getitem__(y) <==> x[y]
|
| __getslice__(...)
| x.__getslice__(i, j) <==> x[i:j]
|
| Use of negative indices is not supported.
|
| __reduce__(...)
|
| __repr__(...)
| x.__repr__() <==> repr(x)
|
| __setattr__(...)
| x.__setattr__('name', value) <==> x.name = value
|
| __setstate__(...)
|
| __str__(...)
| x.__str__() <==> str(x)
|
| __unicode__(...)
|
| ----------------------------------------------------------------------
| Data descriptors inherited from exceptions.BaseException:
|
| __dict__
|
| args
|
| message
FUNCTIONS
compile(pattern, flags=0)
Compile a regular expression pattern, returning a pattern object.
escape(pattern)
Escape all non-alphanumeric characters in pattern.
findall(pattern, string, flags=0)
Return a list of all non-overlapping matches in the string.
If one or more groups are present in the pattern, return a
list of groups; this will be a list of tuples if the pattern
has more than one group.
Empty matches are included in the result.
finditer(pattern, string, flags=0)
Return an iterator over all non-overlapping matches in the
string. For each match, the iterator returns a match object.
Empty matches are included in the result.
match(pattern, string, flags=0)
Try to apply the pattern at the start of the string, returning
a match object, or None if no match was found.
purge()
Clear the regular expression cache
search(pattern, string, flags=0)
Scan through string looking for a match to the pattern, returning
a match object, or None if no match was found.
split(pattern, string, maxsplit=0, flags=0)
Split the source string by the occurrences of the pattern,
returning a list containing the resulting substrings.
sub(pattern, repl, string, count=0, flags=0)
Return the string obtained by replacing the leftmost
non-overlapping occurrences of the pattern in string by the
replacement repl. repl can be either a string or a callable;
if a string, backslash escapes in it are processed. If it is
a callable, it's passed the match object and must return
a replacement string to be used.
subn(pattern, repl, string, count=0, flags=0)
Return a 2-tuple containing (new_string, number).
new_string is the string obtained by replacing the leftmost
non-overlapping occurrences of the pattern in the source
string by the replacement repl. number is the number of
substitutions that were made. repl can be either a string or a
callable; if a string, backslash escapes in it are processed.
If it is a callable, it's passed the match object and must
return a replacement string to be used.
template(pattern, flags=0)
Compile a template pattern, returning a pattern object
DATA
DOTALL = 16
I = 2
IGNORECASE = 2
L = 4
LOCALE = 4
M = 8
MULTILINE = 8
S = 16
U = 32
UNICODE = 32
VERBOSE = 64
X = 64
__all__ = ['match', 'search', 'sub', 'subn', 'split', 'findall', 'comp...
__version__ = '2.2.1'
VERSION
2.2.1
import re
match = re.match("a(b?)+","a")
if not match:
raise ValueError("No match :(")
print match
print match.re
print match.string
print match.group()
print match.start()
print match.end()
<_sre.SRE_Match object at 0x1043937b0> <_sre.SRE_Pattern object at 0x10418d8c8> a a 0 1
Los siguientes caracteres especiales matchean con:
. con cualquier caracter excepto newline^ con el comienzo de una cadena, si se encuentra en modo MULTILINE también lo hace con cada newline$ con el fin de la cadena, o justo antes de una newline* matchea 0 o mas veces con la RE que lo precede: ab* matchea con a, ab, o a seguido de cualquier número de b's+ matchea mas de 0 veces con la RE que lo precede: ab+ matchea con ab, o a seguido de cualquier número (distinto de 0) de b's? ab? con a o ab{m} exactamente con m copias de la RE que lo precede. a{6} solo matchea con aaaaaa{m,n}? matchea desde m a n repeticiones, tratando de que sean la menor cantidad posible. Ej: aaaaaa, a{3,5} con aaaaa mientras que a{3,5}? solo con aaa \ permite matchear caracteres especiales como *, ?A|B siendo A y B cualquier RE, matchea con A o B. Para matchear el literal | usar \|[] permite indicar un set de caracteres[amk] matchea con a o m o k[-] para indicar rangos: [a-z] matchea con cualquier caracter entre a y z, [0-5][0-9] con cualquier numero de dos dígitos desde 00 a 59re.match(patron, cadena, flags): busca coincidencias solo al principio de la cadenare.search(patron, cadena, flags): busca coincidencias en toda la cadenaimport re
cadena = "Cats are smarter than dogs"
#matchObj = re.match('Cat', cadena)
#matchObj = re.match('dogs', cadena)
matchObj = re.search('dogs', cadena)
if matchObj:
print matchObj.group()
else:
print "No match!"
dogs
def regex_nombre(nombre):
regex = "([a-zA-Z]+) (([a-zA-Z]+) )?([a-zA-Z]+)"
# regex = "([a-zA-Z]+){2,3}?"
match = re.match(regex, nombre)
if match:
print "Nombre completo: %s" % (match.group(0))
print "Primer nombre: %s" % (match.group(1))
print "Segundo nombre: %s" % (match.group(2))
print "Tercer nombre: %s" % (match.group(4))
else:
print "No match :("
regex_nombre("Miguel Alfaro")
#regex_nombre("Miguel 1523")
Nombre completo: Miguel Alfaro Primer nombre: Miguel Segundo nombre: None Tercer nombre: Alfaro
Escribir una función que recibe una cadena con el mes y el dia de una fecha dada de la forma Mes dia, por ejemplo: Marzo 3. E indique cual es la fecha entera, el mes y el dia.
>>>regex_fecha("Junio 3")
Fecha: Junio 3
Mes: Junio
Dia: 3
import re
def regex_fecha(fecha):
regex = "([A-Z][a-z]+) ([0-3][0-1])"
match = re.search(regex, fecha)
if match:
print "Fecha: %s" % (match.group(0))
print "Mes: %s" % (match.group(1))
print "Dia: %s" % (match.group(2))
else:
print "No match :("
regex_fecha("Junio 3")
Fecha: Junio 3 Mes: Junio Dia: 3
Escribir una función que reciba un mail y diga si es válido o no
import re
def regex_mail(mail):
regex = "(^[a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)"
match = re.search(regex, mail)
return match is not None
regex_mail("@miguelalfaro@gmail.com")
False
Escribir una función que reciba una lista de saldos de cuentas y devuelva otra lista con aquellos que son negativos usando regex
def regex_saldos(saldos):
regex = "-"
saldos_negativos = []
# for saldo in saldos:
# match = re.search(regex, saldo)
# if match:
# saldos_negativos.append(saldo)
filtro_saldos = lambda saldo: re.match(regex, saldo)
return filter(filtro_saldos, saldos)
# return saldos_negativos
regex_saldos(["-123","123","-42","32"])
['-123', '-42']
Escribir una funcion que reciba una lista de DNI y devuelva True si todos son DNI's validos.
def regex_dni(dnis):
regex = r"\d{8}"
for dni in dnis:
match = re.match(regex, dni)
if not match:
return False
return True
print regex_dni(["37569522", "17594345", "12543645"])
print regex_dni(["37569522", "175", "12543645"])
True False
Soporte para DOM y SAX
import xml.etree.ElementTree as ET
a = ET.Element('a')
a.set("name","A")
b = ET.SubElement(a, 'Soy un hijo de a')
c = ET.SubElement(a, 'c')
d = ET.SubElement(c, 'Y yo soy hijo de c')
tree = ET.ElementTree(a)
ET.dump(tree)
tree.write("archivo_prueba.xml")
print a.attrib
<a name="A"><Soy un hijo de a /><c><Y yo soy hijo de c /></c></a>
{'name': 'A'}
Implementar un script que transforme el archivo materias.txt en xml.
El archivo materias.txt tiene el formato:
6201 - FISICA I A - 60
...
<CD><CM> - <NOMBRE> - <CUPOS>El formato esperado debe ser:
<root>
<departamento codigo="62">
<materia codigo="01" nombre="Física I" cupos="60"/> .....
<materia codigo="cc" nombre="nombre" cupos="xx"/>
</departamento>
</root>
Nota: En caso de ser necesario ver help.
import os
import re
import xml.etree.ElementTree
class Materia(object):
def __init__(self, nombre, codigo, cupos):
self.nombre = nombre
self.codigo = codigo
self.cupos = cupos
def __str__(self):
return self.nombre + "\t" + self.codigo + "\t" + str(self.cupos)
def exportar_materias_por_departamento():
# Cambia el directorio de trabajo.
pattern = r"^(?P<depto>\d{2})(?P<codigo>\d{2}) - (?P<nombre>[\w\s]+) - (?P<cupos>\d+)$"
regex = re.compile(pattern)
path = os.path.join(os.getcwd(), "..", "Archivos de prueba")
os.chdir(path)
# Itera por departamento.
materias_por_depto = {}
with open("materias.txt") as materias:
for materia in materias:
match = regex.match(materia)
if match is None:
continue
depto = match.group("depto")
codigo = match.group("codigo")
cupos = match.group("cupos")
nombre = match.group("nombre")
materias_por_depto[depto] = materias_por_depto.get(depto, []) + [ Materia(nombre, codigo, int(cupos)) ]
root = xml.etree.ElementTree.Element("root")
tree = xml.etree.ElementTree.ElementTree(root)
for depto in materias_por_depto:
xml_depto = xml.etree.ElementTree.SubElement(root, "departamento")
xml_depto.set("codigo", depto)
for materia in materias_por_depto[depto]:
xml_materia = xml.etree.ElementTree.SubElement(xml_depto, "materia")
xml_materia.set("codigo", materia.codigo)
xml_materia.set("nombre", materia.nombre)
xml_materia.set("cupos", str(materia.cupos))
tree.write("materias.xml")
exportar_materias_por_departamento()
Implementar un programa que levante parametros.txt, reciba por parámetro el nombre del atributo a cambiar y guarde el nuevo archivo de configuración como xml.