Added Boolean operators and lowered line lengths

Added Bool operators and and or, and lowered some line lengths.  Also shifted some notes above the code lines to keep with same style and help readability.  Also added a note on list comprehension.  Also added adding to dictionary.
This commit is contained in:
Steven Basart 2014-09-07 02:39:31 -04:00
parent c0d8a18b08
commit 9a909d6a4a

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@ -61,6 +61,17 @@ False
not True # => False not True # => False
not False # => True not False # => True
# Boolean Operators
# Note "and" and "or" are case-sensitive
True and False #=> False
False or True #=> True
# Note with ints
0 and 2 #=> 0
-5 or 0 #=> -5
0 == False #=> True
2 == True #=> False #only 1 == True #=> True
# Equality is == # Equality is ==
1 == 1 # => True 1 == 1 # => True
2 == 1 # => False 2 == 1 # => False
@ -127,7 +138,8 @@ bool({}) #=> False
# Python has a print function # Python has a print function
print("I'm Python. Nice to meet you!") print("I'm Python. Nice to meet you!")
# No need to declare variables before assigning to them. Convention is to use lower_case_with_underscores # No need to declare variables before assigning to them.
# Convention is to use lower_case_with_underscores
some_var = 5 some_var = 5
some_var # => 5 some_var # => 5
@ -176,7 +188,8 @@ li[::-1] # => [3, 4, 2, 1]
del li[2] # li is now [1, 2, 3] del li[2] # li is now [1, 2, 3]
# You can add lists # You can add lists
li + other_li # => [1, 2, 3, 4, 5, 6] - Note: values for li and for other_li are not modified. # Note: values for li and for other_li are not modified.
li + other_li # => [1, 2, 3, 4, 5, 6]
# Concatenate lists with "extend()" # Concatenate lists with "extend()"
li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6] li.extend(other_li) # Now li is [1, 2, 3, 4, 5, 6]
@ -215,14 +228,17 @@ filled_dict = {"one": 1, "two": 2, "three": 3}
# Look up values with [] # Look up values with []
filled_dict["one"] # => 1 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. # Get all keys as a list with "keys()".
list(filled_dict.keys()) # => ["three", "two", "one"] # 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. # Note - Dictionary key ordering is not guaranteed.
# Your results might not match this exactly. # 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. # Get all values as a list with "values()". Once again we need to wrap it in list() to get it out of the iterable.
list(filled_dict.values()) # => [3, 2, 1]
# Note - Same as above regarding key ordering. # Note - Same as above regarding key ordering.
list(filled_dict.values()) # => [3, 2, 1]
# Check for existence of keys in a dictionary with "in" # Check for existence of keys in a dictionary with "in"
"one" in filled_dict # => True "one" in filled_dict # => True
@ -242,6 +258,10 @@ filled_dict.get("four", 4) # => 4
filled_dict.setdefault("five", 5) # filled_dict["five"] is set to 5 filled_dict.setdefault("five", 5) # filled_dict["five"] is set to 5
filled_dict.setdefault("five", 6) # filled_dict["five"] is still 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["four"] = 4 #another way to add to dict
# Remove keys from a dictionary with del # Remove keys from a dictionary with del
del filled_dict["one"] # Removes the key "one" from filled dict del filled_dict["one"] # Removes the key "one" from filled dict
@ -458,6 +478,7 @@ map(add_10, [1, 2, 3]) # => [11, 12, 13]
filter(lambda x: x > 5, [3, 4, 5, 6, 7]) # => [6, 7] filter(lambda x: x > 5, [3, 4, 5, 6, 7]) # => [6, 7]
# We can use list comprehensions for nice maps and filters # 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
[add_10(i) for i in [1, 2, 3]] # => [11, 12, 13] [add_10(i) for i in [1, 2, 3]] # => [11, 12, 13]
[x for x in [3, 4, 5, 6, 7] if x > 5] # => [6, 7] [x for x in [3, 4, 5, 6, 7] if x > 5] # => [6, 7]