summaryrefslogtreecommitdiffhomepage
path: root/python3.html.markdown
diff options
context:
space:
mode:
Diffstat (limited to 'python3.html.markdown')
-rw-r--r--python3.html.markdown63
1 files changed, 38 insertions, 25 deletions
diff --git a/python3.html.markdown b/python3.html.markdown
index 0b4feccc..a112912f 100644
--- a/python3.html.markdown
+++ b/python3.html.markdown
@@ -13,7 +13,7 @@ executable pseudocode.
Feedback would be highly appreciated! You can reach me at [@louiedinh](http://twitter.com/louiedinh) or louiedinh [at] [google's email service]
-Note: This article applies to Python 3 specifically. Check out the other tutorial if you want to learn the old Python 2.7
+Note: This article applies to Python 3 specifically. Check out [here](http://learnxinyminutes.com/docs/python/) if you want to learn the old Python 2.7
```python
@@ -39,7 +39,7 @@ Note: This article applies to Python 3 specifically. Check out the other tutoria
# Except division which returns floats by default
35 / 5 # => 7.0
-# Result of integer division truncated down both for positive and negative.
+# Result of integer division truncated down both for positive and negative.
5 // 3 # => 1
5.0 // 3.0 # => 1.0 # works on floats too
-5 // 3 # => -2
@@ -73,8 +73,8 @@ False or True #=> True
# Note using Bool operators with ints
0 and 2 #=> 0
-5 or 0 #=> -5
-0 == False #=> True
-2 == True #=> False
+0 == False #=> True
+2 == True #=> False
1 == True #=> True
# Equality is ==
@@ -101,6 +101,8 @@ False or True #=> True
# Strings can be added too! But try not to do this.
"Hello " + "world!" # => "Hello world!"
+# Strings can be added without using '+'
+"Hello " "world!" # => "Hello world!"
# A string can be treated like a list of characters
"This is a string"[0] # => 'T'
@@ -143,7 +145,7 @@ bool({}) #=> False
# Python has a print function
print("I'm Python. Nice to meet you!")
-# No need to declare variables before assigning to them.
+# No need to declare variables before assigning to them.
# Convention is to use lower_case_with_underscores
some_var = 5
some_var # => 5
@@ -184,7 +186,7 @@ li[2:] # => [4, 3]
li[:3] # => [1, 2, 4]
# Select every second entry
li[::2] # =>[1, 4]
-# Revert the list
+# Return a reversed copy of the list
li[::-1] # => [3, 4, 2, 1]
# Use any combination of these to make advanced slices
# li[start:end:step]
@@ -194,7 +196,7 @@ del li[2] # li is now [1, 2, 3]
# You can add lists
# Note: values for li and for other_li are not modified.
-li + other_li # => [1, 2, 3, 4, 5, 6]
+li + other_li # => [1, 2, 3, 4, 5, 6]
# Concatenate lists with "extend()"
li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6]
@@ -211,7 +213,7 @@ tup = (1, 2, 3)
tup[0] # => 1
tup[0] = 3 # Raises a TypeError
-# You can do all those list thingies on tuples too
+# You can do most of the list operations on tuples too
len(tup) # => 3
tup + (4, 5, 6) # => (1, 2, 3, 4, 5, 6)
tup[:2] # => (1, 2)
@@ -233,15 +235,15 @@ filled_dict = {"one": 1, "two": 2, "three": 3}
# Look up values with []
filled_dict["one"] # => 1
-# Get all keys as a list with "keys()".
-# We need to wrap the call in list() because we are getting back an iterable. We'll talk about those later.
-# Note - Dictionary key ordering is not guaranteed.
-# Your results might not match this exactly.
+# Get all keys as an iterable with "keys()". We need to wrap the call in list()
+# to turn it into a list. We'll talk about those later. Note - Dictionary key
+# ordering is not guaranteed. Your results might not match this exactly.
list(filled_dict.keys()) # => ["three", "two", "one"]
-# Get all values as a list with "values()". Once again we need to wrap it in list() to get it out of the iterable.
-# Note - Same as above regarding key ordering.
+# Get all values as an iterable with "values()". Once again we need to wrap it
+# in list() to get it out of the iterable. Note - Same as above regarding key
+# ordering.
list(filled_dict.values()) # => [3, 2, 1]
@@ -276,10 +278,10 @@ empty_set = set()
# Initialize a set with a bunch of values. Yeah, it looks a bit like a dict. Sorry.
some_set = {1, 1, 2, 2, 3, 4} # some_set is now {1, 2, 3, 4}
-#Can set new variables to a set
+# Can set new variables to a set
filled_set = some_set
-# Add one more item to the set
+# Add one more item to the set
filled_set.add(5) # filled_set is now {1, 2, 3, 4, 5}
# Do set intersection with &
@@ -326,7 +328,7 @@ for animal in ["dog", "cat", "mouse"]:
print("{} is a mammal".format(animal))
"""
-"range(number)" returns a list of numbers
+"range(number)" returns an iterable of numbers
from zero to the given number
prints:
0
@@ -338,6 +340,18 @@ for i in range(4):
print(i)
"""
+"range(lower, upper)" returns an iterable of numbers
+from the lower number to the upper number
+prints:
+ 4
+ 5
+ 6
+ 7
+"""
+for i in range(4, 8):
+ print(i)
+
+"""
While loops go until a condition is no longer met.
prints:
0
@@ -394,7 +408,6 @@ our_iterator.__next__() # Raises StopIteration
list(filled_dict.keys()) #=> Returns ["one", "two", "three"]
-
####################################################
## 4. Functions
####################################################
@@ -410,7 +423,6 @@ add(5, 6) # => prints out "x is 5 and y is 6" and returns 11
# Another way to call functions is with keyword arguments
add(y=6, x=5) # Keyword arguments can arrive in any order.
-
# You can define functions that take a variable number of
# positional arguments
def varargs(*args):
@@ -418,7 +430,6 @@ def varargs(*args):
varargs(1, 2, 3) # => (1, 2, 3)
-
# You can define functions that take a variable number of
# keyword arguments, as well
def keyword_args(**kwargs):
@@ -447,14 +458,14 @@ all_the_args(**kwargs) # equivalent to foo(a=3, b=4)
all_the_args(*args, **kwargs) # equivalent to foo(1, 2, 3, 4, a=3, b=4)
-# Function Scope
+# Function Scope
x = 5
def setX(num):
# Local var x not the same as global variable x
x = num # => 43
print (x) # => 43
-
+
def setGlobalX(num):
global x
print (x) # => 5
@@ -501,7 +512,9 @@ class Human(object):
# Basic initializer, this is called when this class is instantiated.
# Note that the double leading and trailing underscores denote objects
# or attributes that are used by python but that live in user-controlled
- # namespaces. You should not invent such names on your own.
+ # namespaces. Methods(or objects or attributes) like: __init__, __str__,
+ # __repr__ etc. are called magic methods (or sometimes called dunder methods)
+ # You should not invent such names on your own.
def __init__(self, name):
# Assign the argument to the instance's name attribute
self.name = name
@@ -587,7 +600,7 @@ def double_numbers(iterable):
# double_numbers.
# Note range is a generator too. Creating a list 1-900000000 would take lot of
# time to be made
-# We use a trailing underscore in variable names when we want to use a name that
+# We use a trailing underscore in variable names when we want to use a name that
# would normally collide with a python keyword
range_ = range(1, 900000000)
# will double all numbers until a result >=30 found
@@ -635,8 +648,8 @@ print(say(say_please=True)) # Can you buy me a beer? Please! I am poor :(
* [The Official Docs](http://docs.python.org/3/)
* [Hitchhiker's Guide to Python](http://docs.python-guide.org/en/latest/)
-* [Python Module of the Week](http://pymotw.com/3/)
* [A Crash Course in Python for Scientists](http://nbviewer.ipython.org/5920182)
+* [Python Course](http://www.python-course.eu/index.php)
### Dead Tree