python_cheat_sheet

""" Python Command and Character list
    (from Learn Python the Hardway by Zed Shaw)
    expanded from Lesson 22
"""
				
#Character / Command	What it's called	What it does	example	example2

pydoc <something>	#pydoc	gives you the manual page for something you want to know about in python	pydoc sys	
help()	#help function	use when running python to find help on an object		
print()	#print function	prints to the console whatever is next	print(“Hello World!”)	print(1 + 2)
"	#double quotes	starts and ends a string	print(“Hello World!”)	
 '	#single quotes starts and ends a string	print("Hello World!")	
=	#equals	assigns values to a variable or function	count = 10	i, j, k, numbers = initialize()
#	#pound	comment; blocks out the line from being read by the interpreter	# This is a comment and won't do anything	
;	#semi-colon	let's you separate multiple lines of code on one line	from sys import argv; from os.path import exists; script, from_file, to_file = argv	

:	colon	used for defining things like in functions; tells python you are going to create a new "block" of code" followed by a new line with 4 indented spaces and then code.	def some_function():	
,	comma	separates strings from variables	print "The script is called:", script	
+	plus	adds	2+2 equals 4	
-	minus	subtracts	etc.	
/	slash	divides, allows you to continue a line of code on multiple lines	etc.	
*	asterik	multiplies, wild card	from ex25 import *	
%	1. percent	gives the remainder of a divisor	7 % 6 returns 1	
%	2. String Fornatter	converts something to something in a string	http://docs.python.org/2/library/stdtypes.html#string-formatting-operations	
%d, %r, %s	escape characters	let's you insert the contents of a variable into a string. %d is for display, %r is for debugging, %s is for inserting / converting to a string. there are others as well...	print "You have this many %d potatoes." % potatoes	
( )	paranthesis	for multiple escape character variables, functions	print("Some string {0} {1}".format(variable1, variable2))	some_function()
<	greater than	comparison operator	if buses > cars: print "Too many buses."	
>	less than	comparison operator		
<=	greater than or equal to	comparison operator		
>=	less than or equal to	comparison operator		
==	is equal to	comparison operator		
!=	does not equal	comparison operator		
_	underscore charcter	generally used instead of spaces	number_passengers	
\	backslash	let's you "escape" certain characters in python	print "I have a \"stupid\" cat." print "I am 5'8\" tall."	
\n	newline character (backslash n)	inserts a new line		
\t	tab	inserts a tab	print(""" I'll do a list: \n\t*beer \n\t*chips \n\t*salsa """)	
"""	triple double quotes	lets you type a comment on mulitple lines, as long as you have """ at the begining and end	"""This is some code that does blah blah blah"""	
raw_input()	raw input (built in function)	takes input in the form a string from the user	you can prompt the user by doing: raw_input("user give me some data")	var = raw_input("> ")
input()	input function (built in)	takes input in the form of a integer from the user	age = input("What's your age? ")	
import	import statement	adds native python modules	from sys import argv	
sys	sys module	provides access to some objects used or maintained by the interpreter and to functions that interact strongly with the interpreter	from sys import argv	
argv	argument variable	see pydoc sys	script, filename = argv	
os.path	path module			
exists	exists command	returns true / false if a file exists or not		
int()	convert to integer function	takes a number and makes it an integer	int(3.33) would return 3	
float()	convert to a floating point number	"" makes it a float	float(3) would return 3.0	
open()	open function	built in function for opening files	text = open(some_file)	
read()	read function	reads the contents of the script. see pydoc file	print(text.read())	
close()	close function	closes the file	text.close()	
write(stuff)	write function	writes stuff to the file	text.write(stuff)	
truncate()	truncate function	empties the file	text.truncate()	
seek()	seek	takes you to specific line in a file	def rewind(f): f.seek(0)	
range()	range	adds a range of integers to a list. range(1,6) will return 0, 1, 2, 3, 4, 5. You can also specify the step in the 3rd number eg: range(1,6,2) will return 0, 2, 4	<<<	
append()	append	appends object(s) to the end of the list		
.	period, dot	lets you call functions on variables or string connect multiple functions	open(to_file, 'w').write(indata) OR output.close()	
def	define	defines a function in a script		
return	return	returns something to the console from within a funciton		
[]	brackets	for containing lists / arrays	fruit = ['apples', 'oranges', bananas'] coins = [1, 5, 10, 25]