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bowanggithubbowanggithub
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functional programming done
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12 files changed

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‎decorator.py‎

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import functools
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def log(func):
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@functools.wraps(func)
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def wrapper(*args,**kw):
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print("call %s():" % func.__name__)
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return func(*args, **kw)
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return wrapper
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@log
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def now():
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print("2015-3-25")
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now()
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print(now.__name__)
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def logger(text):
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def decorator(func):
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@functools.wraps(func)
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def wrapper(*args,**kw):
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print("%s %s():" % (text, func.__name__))
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return func(*args,**kw)
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return wrapper
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return decorator
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@logger("DEBUG")
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def today():
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print("2015-3-25")
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today()
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print(today.__name__)
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def beginend(func):
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def wrapper(*args,**kw):
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print("call %s():" % func.__name__)
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func(*args,**kw)
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print("end %s():" % func.__name__)
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return
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return wrapper
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@beginend
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def printdate():
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print("2015-7-3")
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printdate()

‎do_filter.py‎

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def is_odd(n):
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return n%2==1
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L=range(100)
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print(list(filter(is_odd,L)))
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def not_empty(s):
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return s and s.strip()
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print(list(filter(not_empty,["A", "", "B", None, "C", " "])))
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def is_palindrome(n):
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s=str(n)
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return s==s[::-1]
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print(list(filter(is_palindrome,range(1,1000))))

‎do_generator.py‎

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s=(x*x for x in range(5))
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print(s)
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for x in s:
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print(x)
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def fib(max):
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n,a,b=0,0,1
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while n< max:
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yield b
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a,b=b,a+b
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n=n+1
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return "done"
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f=fib(10)
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print("fib(10):",f)
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for x in f:
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print(x)
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g=fib(5)
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while 1:
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try:
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x=next(g)
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print("g:",x)
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except StopIteration as e:
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print("Generator return value:", e.value)
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break
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def triangles():
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y=[1]
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yield y
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while 1:
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y=[y[i]+y[i+1] for i in range(0,len(y)-1)]
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y.append(1)
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y.insert(0,1)
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yield y
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n=0
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for t in triangles():
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print(t)
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n=n+1
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if n==10:
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break

‎do_iter.py‎

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from collections import Iterable, Iterator
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def g():
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yield 1
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yield 2
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yield 3
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print("Iterable? [1,2,3]:", isinstance([1,2,3],Iterable))
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print("Iterable? \'abc\':", isinstance('abc',Iterable))
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print("Iterable? 123:", isinstance(123,Iterable))
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print("Iterable? g():", isinstance(g(),Iterable))
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print("Iterator? [1,2,3]:", isinstance([1,2,3],Iterator))
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print("Interator? iter([1,2,3]):", isinstance(iter([1,2,3]),Iterator))
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print("Iterator? \'abc\':", isinstance('abc',Iterator))
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print("Itertor? 123:", isinstance(123,Iterator))
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print("Itertor? g():", isinstance(g(),Iterator))
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print ("for x in [1,2,3,4,5]:")
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for x in [1,2,3,4,5]:
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print(x)
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print("for x in iter([1,2,3,4,5]:)")
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for x in iter([1,2,3,4,5]):
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print(x)
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print("next():")
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it=iter([1,2,3,4,5])
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print(next(it))
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print(next(it))
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print(next(it))
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print(next(it))
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print(next(it))
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d={"a":1,"b":2, "c":3}
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print("iter key:",d)
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for k in d.keys():
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print("key:", k)
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print("iter value:",d)
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for v in d.values():
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print("value",v)
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print("iter item:",d)
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for k,v in d.items():
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print("item:", k,v)
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print("iter enumerate([\'A\',\'B\',\'C\'])")
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for i,value in enumerate(['A','B','C']):
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print(i,value)
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print("iter [(1,1), (2,4),(3,9)]:")
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for x,y in [(1,1), (2,4),(3,9)]:
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print(x,y)

‎do_listcompr.py‎

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print([x*x for x in range(1,11)])
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print([x*x for x in range(1,11) if x%2 ==0])
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print([m+n for m in "ABC" for n in "XYZ"])
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d = {"x": "A", "y": "B", "z":"C"}
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print([k+"=" +v for k,v in d.items()])
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L=["Hello", "World",18, "IBM", "Apple"]
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print([s.lower() for s in L if isinstance(s,str)])

‎do_map.py‎

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def f(x):
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return x*x
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print(list(map(f,[1,2,3,4,5,6,7,8,9])))

‎do_partial.py‎

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import functools
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int2=functools.partial(int,base=2)
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print("1000000=", int2("1000000"))
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print("1010101=", int2("1010101"))
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‎do_reduce.py‎

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from functools import reduce
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CHAR_TO_INT ={
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"0":0,
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"1":1,
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"2":2,
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"3":3,
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"4":4,
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"5":5,
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"6":6,
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"7":7,
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"8":8,
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"9":9
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}
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def str2int(s):
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ints=map(lambda ch: CHAR_TO_INT[ch],s)
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return reduce(lambda x,y:x*10+y,ints)
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print(str2int("0"))
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print(str2int("12300"))
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print(str2int("0012345"))
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CHAR_TO_FLOAT ={
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"0":0,
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"1":1,
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"2":2,
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"3":3,
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"4":4,
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"5":5,
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"6":6,
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"7":7,
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"8":8,
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"9":9,
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".":-1
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}
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def str2float(s):
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nums=map(lambda ch: CHAR_TO_FLOAT[ch],s)
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point=0
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def to_float(f,n):
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nonlocal point
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if n==-1:
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point=1
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return f
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if point == 0:
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return f*10+n
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else:
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point = point*10
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return f+n/point
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return reduce(to_float,nums,0.0)
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print(str2float("0"))
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print(str2float("123.456"))
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print(str2float("123.45600"))
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print(str2float("0.1234"))
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print(str2float(".1234"))
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print(str2float("120.0034"))
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def normalize(name):
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return name[0:1].upper() + name[1:].lower()
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L1=["adam", "LISA", "barT"]
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print(list(map(normalize,L1)))
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def prod(L):
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return reduce(lambda x,y: x*y, L)
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print("3*5*7*9= ", prod([3,5,7,9]))
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def str22float(s):
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def str2list(s):
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return {"0":0,"1":1,"2":2,"3":3,"4":4,"5":5,"6":6,"7":7,"8":8,"9":9,".":"."}[s]
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ss=list(map(str2list,s))
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l=len(ss)-1-ss.index(".")
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ss.remove(".")
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return reduce(lambda x,y: x*10+y,ss)/10.0**l
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print(str22float("123.4567"))

‎do_slice.py‎

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L=["Michael", "Sarah", "Tracy", "Bob", "Jack"]
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print("L[0:3]= ", L[0:3])
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print("L[:3]= ", L[:3])
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print("L[1:3]= ", L[1:3])
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print("L[-2:]= ", L[-2:])
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R=list(range(100))
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print("R[:10]= ", R[:10])
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print("R[-10:]= ", R[-10:])
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print("R[10:20]= ", R[10:20])
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print("R[:10:2]= ", R[:10:2])
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print("R[::5]= ", R[::5])

‎do_sorted.py‎

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from operator import itemgetter
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L=["bob", "about", "Zoo", "Credit"]
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print(sorted(L))
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print(sorted(L,key=str.lower))
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students =[("Bob",75), ("Adam", 92), ("Bart",66), ("Lisa",88)]
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print(sorted(students,key=itemgetter(0)))
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print(sorted(students,key=lambda t: t[1]))
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print(sorted(students,key=itemgetter(1),reverse=True))

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