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Diffstat (limited to 'python.html.markdown')
| -rw-r--r-- | python.html.markdown | 75 |
1 files changed, 45 insertions, 30 deletions
diff --git a/python.html.markdown b/python.html.markdown index 63547bf6..5572e38e 100644 --- a/python.html.markdown +++ b/python.html.markdown @@ -46,7 +46,7 @@ to Python 2.x. For Python 3.x, take a look at the [Python 3 tutorial](http://lea 2.0 # This is a float 11.0 / 4.0 # => 2.75 ahhh...much better -# 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 @@ -141,12 +141,8 @@ bool("") # => False ## 2. Variables and Collections #################################################### -# Python has a print statement, in all 2.x versions but removed from 3. +# Python has a print statement print "I'm Python. Nice to meet you!" -# Python also has a print function, available in versions 2.7 and 3... -# but for 2.7 you need to add the import (uncommented): -# from __future__ import print_function -print("I'm also Python! ") # No need to declare variables before assigning to them. some_var = 5 # Convention is to use lower_case_with_underscores @@ -195,7 +191,7 @@ li[2:] # => [4, 3] li[:3] # => [1, 2, 4] # Select every second entry li[::2] # =>[1, 4] -# Revert the list +# Reverse a copy of the list li[::-1] # => [3, 4, 2, 1] # Use any combination of these to make advanced slices # li[start:end:step] @@ -316,11 +312,11 @@ some_var = 5 # Here is an if statement. Indentation is significant in python! # prints "some_var is smaller than 10" if some_var > 10: - print("some_var is totally bigger than 10.") + print "some_var is totally bigger than 10." elif some_var < 10: # This elif clause is optional. - print("some_var is smaller than 10.") + print "some_var is smaller than 10." else: # This is optional too. - print("some_var is indeed 10.") + print "some_var is indeed 10." """ @@ -331,8 +327,8 @@ prints: mouse is a mammal """ for animal in ["dog", "cat", "mouse"]: - # You can use % to interpolate formatted strings - print("%s is a mammal" % animal) + # You can use {0} to interpolate formatted strings. (See above.) + print "{0} is a mammal".format(animal) """ "range(number)" returns a list of numbers @@ -344,7 +340,19 @@ prints: 3 """ for i in range(4): - print(i) + print i + +""" +"range(lower, upper)" returns a list 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. @@ -356,7 +364,7 @@ prints: """ x = 0 while x < 4: - print(x) + print x x += 1 # Shorthand for x = x + 1 # Handle exceptions with a try/except block @@ -371,7 +379,13 @@ except (TypeError, NameError): pass # Multiple exceptions can be handled together, if required. else: # Optional clause to the try/except block. Must follow all except blocks print "All good!" # Runs only if the code in try raises no exceptions +finally: # Execute under all circumstances + print "We can clean up resources here" +# Instead of try/finally to cleanup resources you can use a with statement +with open("myfile.txt") as f: + for line in f: + print line #################################################### ## 4. Functions @@ -379,7 +393,7 @@ else: # Optional clause to the try/except block. Must follow all except blocks # Use "def" to create new functions def add(x, y): - print("x is %s and y is %s" % (x, y)) + print "x is {0} and y is {1}".format(x, y) return x + y # Return values with a return statement # Calling functions with parameters @@ -398,7 +412,7 @@ varargs(1, 2, 3) # => (1, 2, 3) # You can define functions that take a variable number of -# keyword args, as well, which will be interpreted as a map if you do not use ** +# keyword args, as well, which will be interpreted as a dict if you do not use ** def keyword_args(**kwargs): return kwargs @@ -408,8 +422,8 @@ keyword_args(big="foot", loch="ness") # => {"big": "foot", "loch": "ness"} # You can do both at once, if you like def all_the_args(*args, **kwargs): - print(args) - print(kwargs) + print args + print kwargs """ all_the_args(1, 2, a=3, b=4) prints: (1, 2) @@ -431,14 +445,14 @@ def pass_all_the_args(*args, **kwargs): print varargs(*args) print keyword_args(**kwargs) -# 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 @@ -489,7 +503,7 @@ class Human(object): # An instance method. All methods take "self" as the first argument def say(self, msg): - return "%s: %s" % (self.name, msg) + return "{0}: {1}".format(self.name, msg) # A class method is shared among all instances # They are called with the calling class as the first argument @@ -505,10 +519,10 @@ class Human(object): # Instantiate a class i = Human(name="Ian") -print(i.say("hi")) # prints out "Ian: hi" +print i.say("hi") # prints out "Ian: hi" j = Human("Joel") -print(j.say("hello")) # prints out "Joel: hello" +print j.say("hello") # prints out "Joel: hello" # Call our class method i.get_species() # => "H. sapiens" @@ -528,12 +542,12 @@ Human.grunt() # => "*grunt*" # You can import modules import math -print(math.sqrt(16)) # => 4 +print math.sqrt(16) # => 4 # You can get specific functions from a module from math import ceil, floor -print(ceil(3.7)) # => 4.0 -print(floor(3.7)) # => 3.0 +print ceil(3.7) # => 4.0 +print floor(3.7) # => 3.0 # You can import all functions from a module. # Warning: this is not recommended @@ -579,7 +593,7 @@ xrange_ = xrange(1, 900000000) # will double all numbers until a result >=30 found for i in double_numbers(xrange_): - print(i) + print i if i >= 30: break @@ -608,24 +622,25 @@ def say(say_please=False): return msg, say_please -print(say()) # Can you buy me a beer? -print(say(say_please=True)) # Can you buy me a beer? Please! I am poor :( +print say() # Can you buy me a beer? +print say(say_please=True) # Can you buy me a beer? Please! I am poor :( ``` ## Ready For More? ### Free Online +* [Automate the Boring Stuff with Python](https://automatetheboringstuff.com) * [Learn Python The Hard Way](http://learnpythonthehardway.org/book/) * [Dive Into Python](http://www.diveintopython.net/) * [The Official Docs](http://docs.python.org/2.6/) * [Hitchhiker's Guide to Python](http://docs.python-guide.org/en/latest/) * [Python Module of the Week](http://pymotw.com/2/) * [A Crash Course in Python for Scientists](http://nbviewer.ipython.org/5920182) +* [First Steps With Python](https://realpython.com/learn/python-first-steps/) ### Dead Tree * [Programming Python](http://www.amazon.com/gp/product/0596158106/ref=as_li_qf_sp_asin_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0596158106&linkCode=as2&tag=homebits04-20) * [Dive Into Python](http://www.amazon.com/gp/product/1441413022/ref=as_li_tf_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=1441413022&linkCode=as2&tag=homebits04-20) * [Python Essential Reference](http://www.amazon.com/gp/product/0672329786/ref=as_li_tf_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=0672329786&linkCode=as2&tag=homebits04-20) - |