PARAMETRIC CULTURE

Built-in Functions in Python

The Python interpreter has a number of functions built into it that are always available. They are listed here in alphabetical order.

In addition, there are other four built-in functions that are no longer considered essential: apply(), buffer(), coerce(), and intern(). They are documented in the Non-essential Built-in Functions section.

abs(x)

Return the absolute value of a number. The argument may be a plain or long integer or a floating point number. If the argument is a complex number, its magnitude is returned.

출처

https://docs.python.org/2/library/functions.html

Loop Mechanisms in Python

메카니즘 설명

x = int(raw_input('Enter an integer: ')) # asks me to enter a value 
                    # for x that I want to find the cube root of
for ans in range(0, abs(x)+1): # tests answers from x = 0 to x ...
                    # Certainly the cube root of x can't be 
                    # greater than x.
    if ans**3 == abs(x): # compares ans**3 with x
        break # if we have the answer, break out of the loop
if ans**3 != abs(x): # if we run past the end of the range, we end
                # up here, so x is not a perfect cube, and we're
                # done.
     print(str(x) + ' is not a perfect cube')
else: # If we don't run out of range, and we have the answer, we
# end up here.
     if x < 0: # If we began with a negative integer, we will have a 
            # negative root. Note that we used abs(x) in the
            # above code to account for this possibility.
         ans = - ans
     print('Cube root of ' + str(x) + ' is ' + str(ans))

심플예제_1

num = 10
while True:
    if num < 7:
        print 'Breaking out of loop'
        break
    print num
    num -= 1
print 'Outside of loop'

Result

10, ,9, 8, 7, "Breaking out of loop", "Outside of loop"

심플예제_2

num = 2
while num < 11:
    print num
    num += 2
print "Goodbye!"

num = 2
while num <= 10:
    print num
    num += 2
print "Goodbye!"

num = 0
while True:
    num += 2
    print num
    if num >= 10:
        print "Goodbye!" 
        break

num = 1
while num <= 10:
    if num % 2 == 0:
        print num
    num += 1
print "Goodbye!"

심플예제_3

print "Hello!"
num = 10
while num > 0:
    print num
    num -= 2

num = 11
print "Hello!"
while num > 1:
    num -= 1
    if num %2 == 0:
        print num

심플예제_4

total = 0

current = 1

while current <= end:

    total += current

    current += 1

print total

More Syntax, Keywords, Functions, Variable Scope

관련자료 다운로드

2_syntax_keyword_vars_scope.pdf

출처

https://courses.edx.org

List of Python Keywords

https://docs.python.org/release/2.3.5/ref/keywords.html

Operator precedence

The following table summarizes the operator precedences in Python, from lowest precedence (least binding) to highest precedence (most binding). Operators in the same box have the same precedence. Unless the syntax is explicitly given, operators are binary. Operators in the same box group left to right (except for comparisons, including tests, which all have the same precedence and chain from left to right — see section Comparisons — and exponentiation, which groups from right to left).

출처

https://docs.python.org/2/reference/expressions.html#operator-precedence

Capitalization, Indentation, String Splicing

Pyhton 툴팁 자료 다운로드

1_caps_indent_splicing.pdf

출처

https://courses.edx.org

The Python 'in' Operator

The operators in and not in test for collection membership (a 'collection' refers to a string, list, tuple or dictionary - don't worry, we will cover lists, tuples and dictionaries soon!). The expression

element in coll

evaluates to True if element is a member of the collection coll, and False otherwise.

The expression

element not in coll

evaluates to True if element is not a member of the collection coll, and False otherwise.

Note this returns the negation of element in coll - that is, the expression element not in coll is equivalent to the expression not (element in coll).

Advanced String Slicing

You've seen in lecture that you can slice a string with a call such as s[i:j], which gives you a portion of string s from index i to index j-1. However this is not the only way to slice a string! If you omit the starting index, Python will assume that you wish to start your slice at index 0. If you omit the ending index, Python will assume you wish to end your slice at the end of the string. Check out this session with the Python shell:

>>> s = 'Python is Fun!'
>>> s[1:5]
'ytho'
>>> s[:5]
'Pytho'
>>> s[1:]
'ython is Fun!'
>>> s[:]
'Python is Fun!'

That last example is interesting! If you omit both the start and ending index, you get your original string!

There's one other cool thing you can do with string slicing. You can add a third parameter, k, like this:s[i:j:k]. This gives a slice of the string s from index i to index j-1, with step size k. Check out the following examples:

>>> s = 'Python is Fun!'
>>> s[1:12:2]
'yhni u'
>>> s[1:12:3]
'yoiF'
>>> s[::2]
'Pto sFn'

The last example is similar to the example s[:]. With s[::2], we're asking for the full string s (from index 0 through 13), with a step size of 2 - so we end up with every other character in s. Pretty cool!

출처

https://courses.edx.org