diff options
Diffstat (limited to 'python3.html.markdown')
| -rw-r--r-- | python3.html.markdown | 28 |
1 files changed, 18 insertions, 10 deletions
diff --git a/python3.html.markdown b/python3.html.markdown index 2398e7ac..2e37fccb 100644 --- a/python3.html.markdown +++ b/python3.html.markdown @@ -97,13 +97,13 @@ False or True # => True 1 < 2 < 3 # => True 2 < 3 < 2 # => False -# (is vs. ==) is checks if two variable refer to the same object, but == checks +# (is vs. ==) is checks if two variables refer to the same object, but == checks # if the objects pointed to have the same values. a = [1, 2, 3, 4] # Point a at a new list, [1, 2, 3, 4] b = a # Point b at what a is pointing to b is a # => True, a and b refer to the same object b == a # => True, a's and b's objects are equal -b = [1, 2, 3, 4] # Point a at a new list, [1, 2, 3, 4] +b = [1, 2, 3, 4] # Point b at a new list, [1, 2, 3, 4] b is a # => False, a and b do not refer to the same object b == a # => True, a's and b's objects are equal @@ -174,6 +174,10 @@ some_var # => 5 # See Control Flow to learn more about exception handling. some_unknown_var # Raises a NameError +# if can be used as an expression +# Equivalent of C's '?:' ternary operator +"yahoo!" if 3 > 2 else 2 # => "yahoo!" + # Lists store sequences li = [] # You can start with a prefilled list @@ -224,8 +228,8 @@ li.remove(2) # Raises a ValueError as 2 is not in the list # Insert an element at a specific index li.insert(1, 2) # li is now [1, 2, 3] again -# Get the index of the first item found -li.index(2) # => 3 +# Get the index of the first item found matching the argument +li.index(2) # => 1 li.index(4) # Raises a ValueError as 4 is not in the list # You can add lists @@ -425,7 +429,6 @@ by step. If step is not indicated, the default value is 1. prints: 4 6 - 8 """ for i in range(4, 8, 2): print(i) @@ -584,12 +587,11 @@ add_10(3) # => 13 (lambda x: x > 2)(3) # => True (lambda x, y: x ** 2 + y ** 2)(2, 1) # => 5 -# TODO - Fix for iterables # There are built-in higher order functions -map(add_10, [1, 2, 3]) # => [11, 12, 13] -map(max, [1, 2, 3], [4, 2, 1]) # => [4, 2, 3] +list(map(add_10, [1, 2, 3])) # => [11, 12, 13] +list(map(max, [1, 2, 3], [4, 2, 1])) # => [4, 2, 3] -filter(lambda x: x > 5, [3, 4, 5, 6, 7]) # => [6, 7] +list(filter(lambda x: x > 5, [3, 4, 5, 6, 7])) # => [6, 7] # We can use list comprehensions for nice maps and filters # List comprehension stores the output as a list which can itself be a nested list @@ -689,7 +691,7 @@ i.age # => raises an AttributeError # You can import modules import math -print(math.sqrt(16)) # => 4 +print(math.sqrt(16)) # => 4.0 # You can get specific functions from a module from math import ceil, floor @@ -713,6 +715,11 @@ math.sqrt(16) == m.sqrt(16) # => True import math dir(math) +# If you have a Python script named math.py in the same +# folder as your current script, the file math.py will +# be loaded instead of the built-in Python module. +# This happens because the local folder has priority +# over Python's built-in libraries. #################################################### ## 7. Advanced @@ -781,6 +788,7 @@ print(say(say_please=True)) # Can you buy me a beer? Please! I am poor :( * [A curated list of awesome Python frameworks, libraries and software](https://github.com/vinta/awesome-python) * [30 Python Language Features and Tricks You May Not Know About](http://sahandsaba.com/thirty-python-language-features-and-tricks-you-may-not-know.html) * [Official Style Guide for Python](https://www.python.org/dev/peps/pep-0008/) +* [Python 3 Computer Science Circles](http://cscircles.cemc.uwaterloo.ca/) ### Dead Tree |