Section 1
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Extend a string over multiple lines
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Date created
Mar 1, 2020
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Section 1
(50 cards)
Extend a string over multiple lines
Use triple quotes: s = """ blah blah blah """
access 7 in aList = [42, [1, 2, 7]]
aList[1][ 2]
To create an instance from a module
1. import the module import math 2. create instance using module name: myObj = math.set()
Indicator of list in the initialization phase
[]
shift left and right by n bits
x << n, x >> n
start index of list
0
bitwise and, or, not:
x & y, x or y, ~x
divmod(x, y)
the pair (x // y, x % y)
Length of a list
len(aList)
Initialize dict:
- dict1 = {} dict1['list'] = 'a collection' -dict = {'list' : 'a collection'}
append a list to another list
aList.append(another) print aList [42, [1, 2, 3]] (The list itself got appended, not the members). Note the difference with join(+)
another[:2]
Sublist ending at index 2
store format string in a ...
string variable s = "The sum of %d, %d, %d is %d" print s % (v, x, y)
Populate a list with multiples of same value
zeroList = [0] * 5
int(x), long(x), float(x), complex(x, y)
converting a number to int, long, float, complex
What indexes tuples
square brackets: [] aTuple[2]
List of keys in a dictionary
dict1.keys() dict.values()
Negative index in list
Access members from the end of the list
iterate through lines in the file
for line in file_handler:
bitwise xor
x ^ y
We initialize dictionary with ... and access using ...
Initialize: {} Access: []
Make a number complex
Append a J at the end: a = 1J (the real part will be zero) a.real, a.imag
create empty list
aList = []
Convert to int / float / str
(int)a / (float)a / (str)a
Unlike tuples strings are
Appendable using +. This results in a new string
dict contents as list of tuples (tuple is like a little list)
dict.items()
(Array = vector) is a ... list
Fixed size
3 in another
Test for containment
a = 'hello and goodbye'.split()
split string on whitespace to return a list
Can we change tuples after creation?
No. they are immutable. Cannot change or append to them
Can you change values of chars within a string?
No
print list
print aList
another[-1]
get the last item
and, or, not
a and b a or b not a
pow(x, y) x ** y
x to the power y
remove element i of list aList
del aList[i]
Change the content of an index
another[2] = 8
create non-empty list
another = [1, 2, 3]
Concatenation, repetition, and appending in dictionaries ...
Does not work
What defines tuples
Parentheses containing comma seperated list of values: aTuple = (1, 3, 5)
strings are like list of chars, but strings are
immutable
Operator to access list member by index
[]
x // y
(floored) quotient of x and y
Make a number long
append L at the end: a = 1L
stack, queue, bag, set
Not built in
abs(x)
absolute value or magnitude of x
another[2:]
Sublist starting from index 2
Append a number to a list
aList.append(42)
Open file for reading
file_handler = open('file_name', 'r')
Concatinate (join) two lists
newList = aList + another (note the diff with append)
Section 2
(27 cards)