Python Flashcards
Learn all about the python programming language
Where is the python interpreter usually installed?
The Python interpreter is usually installed as /usr/local/bin/python3.4 file path.
How do you set the python interpreter path to C:\python3.4
set path=%path%;C:\python3.4
When inside the python terminal, how do you quit?
quit()
How do you start a comment in python?
#
What are the symbols of add, subtract, multiply, divide and remainder in python?
+, -, *, /, and %
Just as in BODMAS, python respects parenthesis.
which will be treated first: (50 - 5*6) / 4 ?
The Multiplication in the bracket, followed by the subtraction and the total will be divided by 4
5 ** 2 ?
25
> > > width = 20
height = 5 * 2
width * height
200
How do you escape single quotes in ‘doesn’t’ ? to give “doesn’t”
‘doesn't’
s = ‘First line.\nSecond line.’ without print(), produces what?
‘First line.\nSecond line.’
s = ‘First line.\nSecond line.’ with print(s), produces what?
First line.
Second line.
What does r in print(r’C:\some\name’) does?
If you don’t want characters prefaced by \ to be interpreted as special characters, you can use raw strings by adding an r before the first quote
output: C:\some\name
String Literals allow multi-line comments, how do you write them?
”””\
Usage: thingy [OPTIONS]
-h Display this usage message
-H hostname Hostname to connect to
“””
3 * ‘un’ + ‘ium’ produces?
‘unununium’
# 3 times ‘un’, followed by ‘ium’
‘Py’ ‘thon’ returns what?
‘Python’ because of the string literal. A variable and a string literal would not work
A variable text with a string literal in parenthesis:
text = (‘Put several strings within parentheses ‘
‘to have them joined together.’), returns what?
‘Put several strings within parentheses to have them joined together.’
word = ‘Python’
word[0] # character in position 0
Returns what?
‘P’
word = ‘Python’
word[5] # character in position 5
Returns what?
‘n’
word = ‘Python’
word[-1] # last character
Returns what?
‘n’
word = ‘Python’
word[-2] # second-last character
Returns what?
‘o’
word = ‘Python’
word[-6]
Returns what?
‘P’
word = ‘Python’
word[0:2] # characters from position 0 (included) to 2 (excluded)
Returns what?
‘Py’
word = ‘Python’
word[2:5] # characters from position 2 (included) to 5 (excluded)
Returns what?
‘tho’
s[:i] + s[i:] = s
word = ‘Python’
word[:2] + word[2:]
Returns what?
‘Python’
word = ‘Python’
word[:4] + word[4:]
Returns what?
‘Python’
One way to remember how slices work is to think of the indices as pointing between characters, with the left edge of the first character numbered 0. Then the right edge of the last character of a string of n characters has index n. Draw a diagram using ‘Python’ sliced
+—+—+—+—+—+—+
| P | y | t | h | o | n |
+—+—+—+—+—+—+
0 1 2 3 4 5 6
-6 -5 -4 -3 -2 -1
‘J’ + word[1:] changes what letter in ‘Python’ ?
‘Jython’
word[0] = ‘J’ What does this give you?
TypeError: ‘str’ object does not support item assignment
word[2:] = ‘py’ What does this give you?
TypeError: ‘str’ object does not support item assignment
word[:2] + ‘py’ changes what letter in ‘Python’ ?
‘Pypy’
s = ‘supercalifragilisticexpialidocious’
Output: 34
How do we get this?
len(s)
> > > squares = [1, 4, 9, 16, 25]
squares
Output?
[1, 4, 9, 16, 25]
> > > squares = [1, 4, 9, 16, 25]
squares[0] # indexing returns the item
Output?
1
> > > squares = [1, 4, 9, 16, 25]
squares[-1]
Output?
25
> > > squares = [1, 4, 9, 16, 25]
squares[-3]
Output?
[9, 16, 25]
> > > squares = [1, 4, 9, 16, 25]
squares[:]
Output?
[1, 4, 9, 16, 25]
> > > squares = [1, 4, 9, 16, 25]
squares + [36, 49, 64, 81, 100]
Output?
[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]
> > > cubes = [1, 8, 27, 65, 125] # something’s wrong here
4 ** 3 # the cube of 4 is 64, not 65!
Correct this!
cubes[3] = 64 # replace the wrong value
»> cubes
[1, 8, 27, 64, 125]
> > > cubes = [1, 8, 27, 65, 125, , ]
Missing Values, what happened?
Output = [1, 8, 27, 64, 125, 216, 343]
> > > cubes.append(216) # add the cube of 6
cubes.append(7 ** 3) # and the cube of 7
cubes
[1, 8, 27, 64, 125, 216, 343]
> > > letters = [‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’, ‘g’]
letters
[‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’, ‘g’]
# replace some values
letters[2:5] = [‘C’, ‘D’, ‘E’]
letters
Output?
Output = [‘a’, ‘b’, ‘C’, ‘D’, ‘E’, ‘f’, ‘g’]
[‘a’, ‘b’, ‘C’, ‘D’, ‘E’, ‘f’, ‘g’]
»> # now remove them
»> letters[2:5] = []
»> letters
Output?
Output = [‘a’, ‘b’, ‘f’, ‘g’]
> > > letters = [‘a’, ‘b’, ‘c’, ‘d’, ‘e’, ‘f’, ‘g’]
letters[:] = []
letters
output?
[]
> > > letters = [‘a’, ‘b’, ‘c’, ‘d’]
len(letters)
4
> > > a = [‘a’, ‘b’, ‘c’]
n = [1, 2, 3]
x = [a, n]
x
What is x?
x = [[‘a’, ‘b’, ‘c’], [1, 2, 3]]
> > > a = [‘a’, ‘b’, ‘c’]
n = [1, 2, 3]
x = [a, n]
x[0]
Output?
[‘a’, ‘b’, ‘c’]
