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-rw-r--r--python3.html.markdown67
1 files changed, 47 insertions, 20 deletions
diff --git a/python3.html.markdown b/python3.html.markdown
index 87fa0b70..85f16858 100644
--- a/python3.html.markdown
+++ b/python3.html.markdown
@@ -68,15 +68,15 @@ not False # => True
# Boolean Operators
# Note "and" and "or" are case-sensitive
-True and False #=> False
-False or True #=> True
+True and False # => False
+False or True # => True
# Note using Bool operators with ints
-0 and 2 #=> 0
--5 or 0 #=> -5
-0 == False #=> True
-2 == True #=> False
-1 == True #=> True
+0 and 2 # => 0
+-5 or 0 # => -5
+0 == False # => True
+2 == True # => False
+1 == True # => True
# Equality is ==
1 == 1 # => True
@@ -123,10 +123,10 @@ b == a # => True, a's and b's objects are equal
# You can repeat the formatting arguments to save some typing.
"{0} be nimble, {0} be quick, {0} jump over the {1}".format("Jack", "candle stick")
-#=> "Jack be nimble, Jack be quick, Jack jump over the candle stick"
+# => "Jack be nimble, Jack be quick, Jack jump over the candle stick"
# You can use keywords if you don't want to count.
-"{name} wants to eat {food}".format(name="Bob", food="lasagna") #=> "Bob wants to eat lasagna"
+"{name} wants to eat {food}".format(name="Bob", food="lasagna") # => "Bob wants to eat lasagna"
# If your Python 3 code also needs to run on Python 2.5 and below, you can also
# still use the old style of formatting:
@@ -145,8 +145,8 @@ None is None # => True
# All other values are True
bool(0) # => False
bool("") # => False
-bool([]) #=> False
-bool({}) #=> False
+bool([]) # => False
+bool({}) # => False
####################################################
@@ -212,6 +212,17 @@ li2 = li[:] # => li2 = [1, 2, 4, 3] but (li2 is li) will result in false.
# Remove arbitrary elements from a list with "del"
del li[2] # li is now [1, 2, 3]
+# Remove first occurrence of a value
+li.remove(2) # li is now [1, 3]
+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
+li.index(4) # Raises a ValueError as 4 is not in the list
+
# You can add lists
# Note: values for li and for other_li are not modified.
li + other_li # => [1, 2, 3, 4, 5, 6]
@@ -244,11 +255,13 @@ tup[:2] # => (1, 2)
2 in tup # => True
# You can unpack tuples (or lists) into variables
-a, b, c = (1, 2, 3) # a is now 1, b is now 2 and c is now 3
+a, b, c = (1, 2, 3) # a is now 1, b is now 2 and c is now 3
+# You can also do extended unpacking
+a, *b, c = (1, 2, 3, 4) # a is now 1, b is now [2, 3] and c is now 4
# Tuples are created by default if you leave out the parentheses
d, e, f = 4, 5, 6
# Now look how easy it is to swap two values
-e, d = d, e # d is now 5 and e is now 4
+e, d = d, e # d is now 5 and e is now 4
# Dictionaries store mappings
@@ -296,12 +309,17 @@ filled_dict.setdefault("five", 5) # filled_dict["five"] is set to 5
filled_dict.setdefault("five", 6) # filled_dict["five"] is still 5
# Adding to a dictionary
-filled_dict.update({"four":4}) #=> {"one": 1, "two": 2, "three": 3, "four": 4}
+filled_dict.update({"four":4}) # => {"one": 1, "two": 2, "three": 3, "four": 4}
#filled_dict["four"] = 4 #another way to add to dict
# Remove keys from a dictionary with del
del filled_dict["one"] # Removes the key "one" from filled dict
+# From Python 3.5 you can also use the additional unpacking options
+{'a': 1, **{'b': 2}} # => {'a': 1, 'b': 2}
+{'a': 1, **{'a': 2}} # => {'a': 2}
+
+
# Sets store ... well sets
empty_set = set()
@@ -326,7 +344,16 @@ filled_set & other_set # => {3, 4, 5}
filled_set | other_set # => {1, 2, 3, 4, 5, 6}
# Do set difference with -
-{1, 2, 3, 4} - {2, 3, 5} # => {1, 4}
+{1, 2, 3, 4} - {2, 3, 5} # => {1, 4}
+
+# Do set symmetric difference with ^
+{1, 2, 3, 4} ^ {2, 3, 5} # => {1, 4, 5}
+
+# Check if set on the left is a superset of set on the right
+{1, 2} >= {1, 2, 3} # => False
+
+# Check if set on the left is a subset of set on the right
+{1, 2} <= {1, 2, 3} # => True
# Check for existence in a set with in
2 in filled_set # => True
@@ -435,7 +462,7 @@ with open("myfile.txt") as f:
filled_dict = {"one": 1, "two": 2, "three": 3}
our_iterable = filled_dict.keys()
-print(our_iterable) #=> range(1,10). This is an object that implements our Iterable interface
+print(our_iterable) # => range(1,10). This is an object that implements our Iterable interface
# We can loop over it.
for i in our_iterable:
@@ -449,17 +476,17 @@ our_iterator = iter(our_iterable)
# Our iterator is an object that can remember the state as we traverse through it.
# We get the next object with "next()".
-next(our_iterator) #=> "one"
+next(our_iterator) # => "one"
# It maintains state as we iterate.
-next(our_iterator) #=> "two"
-next(our_iterator) #=> "three"
+next(our_iterator) # => "two"
+next(our_iterator) # => "three"
# After the iterator has returned all of its data, it gives you a StopIterator Exception
next(our_iterator) # Raises StopIteration
# You can grab all the elements of an iterator by calling list() on it.
-list(filled_dict.keys()) #=> Returns ["one", "two", "three"]
+list(filled_dict.keys()) # => Returns ["one", "two", "three"]
####################################################