Python Day #2

a = [2,10,4,3,7]
a.sort()
print(a)

# returns a new sorted list without modifying source list
a = [2,10,4,3,7]
print(sorted(a))
print(a)

# sort method with different type of objects
a = ["hello", 1, "world", 45, 2]
# a.sort() comparing int 2 str s not allowed in Python 3.x
print(a)

# function as a sort key
a = [[2,3], [4,6], [6,1]]
a.sort(key=lambda x: x[1])
print(a)

a = ['python', 'perl', 'java', 'c', 'haskell', 'ruby']

# sorts a list of strings based on length
def lensort(a):
    a.sort(key=len)
    print(a)

lensort(a)

a = ['python', 'java', 'Python', 'Java']

# sorts a list of unique string
def unique(a):
    u = list(set(word.lower() for word in a))
    u.sort()
    print(u)

unique(a)

# tuples
a = (1,2,3)
print(a[0])

a = 1,2,3
print(a[1])

print(len(a))
print(a[0:])
print(a[1:])

# sets
x = set([3,1,2,1])
print(x)

# other way of writing sets
x = {3,2,1,3} # no need to use set word
print(x)

# add elements to a set using add method
x = set([1,2,3])
x.add(4)
print(x)

# existence of an element using in operator
x = set([1,2,3])
print(1 in x)
print(5 in x)

# strings
print(len("abrakadabra"))

a = "hello world"
print(a[-4])
print(a[::-1])

print(a.split()) # creating a list

b = "a,b,c"
print(b.split(',')) # like above

c = "hello"
d = "world"
print(" ".join([c,d])) # join strings

print(b.strip(' world')) # strip letter

# formating values into strings
print("%s %s" % (c,d))
print('Cahpter %d: %s' % (3, 'Data Structures'))

# sorting by extension
a = ['a.c', 'a.py', 'b.py', 'bar.txt', 'foo.txt', 'x.c']

import os.path

def extsort(a):
    a.sort(key=lambda f: os.path.splitext(f))
    print(a)

extsort(a)