The document discusses several advanced Python concepts including regular expressions, lambda functions, threading, and more. It covers matching, searching, and finding patterns in strings using regular expressions. Lambda functions are described as anonymous functions. Threading allows running functions concurrently using threads to improve performance. Map and filter functions are also overviewed by applying functions to lists.

1. [PYTHON CONCEPTS]
Advanced concepts
OCTOBER 7, 2015
P.D.MANUSHA DILAN
manushadilan@gmail.com

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Contents
I. #re Module ……………………………………………………………………………… 2
a. #match
b. #search
c. #findall
d. #sub
II. #lambda functions …………………………………………………………… 5
a. #map
b. #filter
III. #threading .…………………………………………………………………………… 8

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#re Module
using for regular expressions
#match
#match with first location of the string
#variable=re.match(pattern,String,optional flags)
import re
mystr="Good programmer should learn Python2,Python3,Perl,Java,Javascript and C"
a=re.match("Good",mystr)
print(a)
<_sre.SRE_Match object; span=(0, 4), match='Good'>
print(type(a))
<class '_sre.SRE_Match'>
print(a.group())
Good
x=re.match("abc",mystr)
print(x)
None

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a=re.match("good",mystr,re.I)
print(a)
print(a.group())
<_sre.SRE_Match object; span=(0, 4), match='Good'>
Good
#search
#search the entire string
#variable=re.search(pattern,String,optional flags)
arp="22.22.22.1 0 b4:a9:5a:ff:c8:45 VLAN#222 L"
s=re.search(r"(.+?) +(d) +(.+?)s{2,}(w)*",arp)
print(s.group(1))
22.22.22.1
s1=re.search(r"(.+) +(d) +(.+?)s{2,}(w)*",arp)
print(s1.group(1))
print(s.group(2))
print(s.group(3))
print(s.group(4))
22.22.22.1
0
b4:a9:5a:ff:c8:45 VLAN#222
L

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print(s.group())
print(s.group(0))
print(s.groups())
22.22.22.1 0 b4:a9:5a:ff:c8:45 VLAN#222 L
22.22.22.1 0 b4:a9:5a:ff:c8:45 VLAN#222 L
('22.22.22.1', '0', 'b4:a9:5a:ff:c8:45 VLAN#222', 'L')
#findall
f=re.findall(r"dd.d{2}.[0-9][0-9].[0-9]{1,3}",arp)
print(f)
print(type(f))
['22.22.22.1']
<class 'list'>
f=re.findall(r"(dd).(d{2}).([0-9][0-9]).([0-9]{1,3})",arp)
print(f)
[('22', '22', '22', '1')]
arp2="22.22.22.1 0 b4:a9:5a:ff:c8:45 VLAN#222 L 10.10.10.10"
f=re.findall(r"(dd).(d{2}).([0-9][0-9]).([0-9]{1,3})",arp2)
print(f)
[('22', '22', '22', '1'), ('10', '10', '10', '10')]
#sub
b=re.sub(r"d","7",arp2)
print(b)
77.77.77.7 7 b7:a7:7a:ff:c7:77 VLAN#777 L 77.77.77.77

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#lambda functions (anonymous functions)
lambda arg1,arg2,....,argN: expression using arguments
a=lambda x,y:x*y
print(a)
print(type(a))
<function <lambda> at 0x03C8C8A0>
<class 'function'>
print(a(2,10))
20
b=lambda list:[x*y for x in range(10) for y in range(5)]+list
print(b([44,66,67]))
[0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 0, 2, 4, 6, 8, 0, 3, 6, 9, 12, 0, 4, 8, 12, 16, 0, 5, 10, 15, 20, 0, 6, 12,
18, 24, 0, 7, 14, 21, 28, 0, 8, 16, 24, 32, 0, 9, 18, 27, 36, 44, 66, 67]

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#map
#map(function, sequence)
#return the result of function applied to all items in sequence
def product10(a):
return a*10
list1=range(10)
m=map(product10,list1)
print(m)
<map object at 0x03C64CB0>
for i in m:
print(i)
0 10 20 30 40 50 60 70 80 90
m2=map((lambda a:a*10),list1)
for i in m2:
print(i)
10 20 30 40 50 60 70 80 90

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#filter
#filter(function, sequence)
#return all items in sequence for which function is true
f=filter(lambda a:a>5,list1)
for i in f:
print(i)
6 7 8 9

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#threading
basic concept of threading
import threading
import time
def myfunc():
print("Start a thread !n")
time.sleep(3)
print("End a thread !!n")
threads=[]
for i in range(5):
th=threading.Thread(target=myfunc)
th.start()
threads.append(th)
for th in threads:
th.join()
Start a thread !
Start a thread !
Start a thread !
Start a thread !
Start a thread !

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End a thread !!
End a thread !!
End a thread !!
End a thread !!
End a thread !!
#without threading
import time
def myfunc():
print("Start a thread !n")
time.sleep(3)
print("End a thread !!n")
for i in range(5):
myfunc()
Start a thread !
End a thread !!
Start a thread !
End a thread !!
Start a thread !
End a thread !!
Start a thread !
End a thread !!
Start a thread !
End a thread !!