Python: Basics - Revision history

Ittichai at 18:42, 20 October 2013

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Ittichai at 23:11, 8 April 2013

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Ittichai at 23:10, 8 April 2013

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Ittichai at 23:10, 8 April 2013

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Ittichai at 23:09, 8 April 2013

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Ittichai at 23:09, 8 April 2013

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Ittichai at 23:08, 8 April 2013

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Ittichai at 23:08, 8 April 2013

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Ittichai: Created page with "* Comment ** Single-line comment

  # Hello World

** Multiple-line comment

  """"Hello  World"""

* Functions

  .isalpha()    # Check if alpha ..."

2013-04-08T23:00:03Z

Created page with "* Comment ** Single-line comment <pre> # Hello World </pre> ** Multiple-line comment <pre> """"Hello World""" </pre> * Functions <pre> .isalpha() # Check if alpha ..."

New page

* Comment

** Single-line comment

<pre>

# Hello World

</pre>

** Multiple-line comment

<pre>

""""Hello

World"""

</pre>

* Functions

<pre>

.isalpha() # Check if alpha characters

<pre>

* Create a function

<pre>

def <function_name> ():

def <function_name> (arg):

def <function_name> (arg1, arg2):

def <function_name> (*args): # Multiple/unknown # of arguments, arbitrary number of arguments

sum(args) # You add arguments up

</pre>

* Import defined functions

<pre>

from <module> import <function>

Sample:

import math # Import all, use math.sqrt

math import sqrt # Import only sqrt, no need to qualify

from math import * # Just import metadata??

import this # Easter Egg - The Zen of Python

</pre>

* If-then-else on one line

<pre>

Boolean = True if (1 == 2) else False

if :

elif :

else:

</pre>

* List

<pre>

<list_name> = [] # Empty list

<list_name>.append(<item>)

</pre>

* List samples

<pre>

my_list.index("dog") # Return the first index that contains the string “dog”

my_list.insert(4,"cat") # Add item “cat” at index 4 and bump the rest forward

</pre>

* For loop the list

<pre>

my_list = [1,9,3,8,5,7]

for number in my_list:

print number * 2

my_list.sort()

</pre>

* Remove item from the list

** n.pop(index) will remove the item at index from the list and return it to you:

<pre>

n = [1, 3, 5]
n.pop(1)
# Returns 3 (the item at index 1)
print n
# prints [1, 5]
</pre>

** n.remove(item) will remove the actual item if it finds it:

<pre>

n.remove(1)
# Removes 1 from the list,
# NOT the item at index 1
print n
# prints [3, 5]
</pre>

** del(n[1] is like .pop in that it will remove the item at the given index, but it won't return it:

<pre>

del(n[1])
# Doesn't return anything
print n
# prints [1, 5]

</pre>

* Dictionary

<pre>

d = {'key1' : 1, 'key2' : 2, 'key3' : 3}

</pre>

* Dictionary sample

<pre>

menu = {} # Empty dictionary

menu['Chicken Alfredo'] = 14.50 # Adding new key-value pair

def plane_ride_cost(city):
data = {"Charlotte": 183, "Tampa": 220, "Pittsburgh": 222, "Los Angeles": 475}
return data[city]

</pre>

* Remove item in dictionary

** del deletes a key and its value based on the key you tell it to delete

<pre>

del dict_name[key_name]

</pre>

** .remove() removes a key and its value based on the value you tell it to delete.

<pre>

my_list.remove(value)

</pre>

* More dictionary samples

<pre>

inventory = {'gold' : 500,

'pouch' : ['flint', 'twine', 'gemstone'], # Assigned a new list to 'pouch' key

'backpack' : ['xylophone','dagger', 'bedroll','bread loaf']}

# Adding a key 'burlap bag' and assigning a list to it

inventory['burlap bag'] = ['apple', 'small ruby', 'three-toed sloth']

# Sorting the list found under the key 'pouch'

inventory['pouch'].sort()

# Here the dictionary access expression takes the place of a list name

inventory['pocket'] = ['seashell', 'strange berry', 'lint']

inventory['backpack'].sort()

inventory['backpack'].remove('dagger')

inventory['gold'] = inventory['gold']+50

</pre>

* Dictionaries are unordered

<pre>

d => {"foo" : "bar"}

for key in d:
print d[key] # prints "bar"
</pre>

* Print vertically

<pre>

for letter in "Codecademy":

print letter

C
o
d
e
c
a
d
e
m
y

</pre>

<pre>

def average(alist):

return sum(alist)/len(alist)

score = round(score)

</pre>

* Random modul

<pre>

from random import randrange

# Generate a

random_number = randrange(1, 10)

</pre>

* Enumerate

<pre>

choices = ['pizza', 'pasta', 'salad', 'nachos']

print 'Your choices are:'

for index, item in enumerate(choices):

print index+1, item

</pre>

* Zip

** It's also common to need to iterate over two lists at once. This is where the built-in zip function comes in handy.

** Zip will create pairs of elements when passed two lists, and will stop at the end of the shorter list.

** Zip can handle three or more lists as well!

<pre>

list_a = [3, 9, 17, 15, 19]

list_b = [2, 4, 8, 10, 30, 40, 50, 60, 70, 80, 90]

for a, b in zip(list_a, list_b):

# Add your code here!

print a, b

</pre>

← Older revision		Revision as of 18:42, 20 October 2013
Line 198:		Line 198:
	print a, b		print a, b
	</pre>		</pre>
		+
		+	[[Category:Python]]

@@ Line 166: / Line 166: @@
 </pre>
-* Random modul
+* Random module
 <pre>

@@ Line 104: / Line 104: @@
      return data[city]
 </pre>
-* Remove item in dictionary
+Remove item in dictionary
-** del deletes a key and its value based on the key you tell it to delete
+* del deletes a key and its value based on the key you tell it to delete
 <pre>
 del dict_name[key_name]
 </pre>
-** .remove() removes a key and its value based on the value you tell it to delete.
+* .remove() removes a key and its value based on the value you tell it to delete.
 <pre>
 my_list.remove(value)

@@ Line 64: / Line 64: @@
 my_list.sort()
 </pre>
-* Remove item from the list
 * n.pop(index) will remove the item at index from the list and return it to you:
 <pre>

@@ Line 65: / Line 65: @@
 </pre>
 * Remove item from the list
-** n.pop(index) will remove the item at index from the list and return it to you:
+* n.pop(index) will remove the item at index from the list and return it to you:
 <pre>
 n = [1, 3, 5]
@@ Line 73: / Line 73: @@
 # prints [1, 5]
 </pre>
-** n.remove(item) will remove the actual item if it finds it:
+* n.remove(item) will remove the actual item if it finds it:
 <pre>
 n.remove(1)
@@ Line 81: / Line 81: @@
 # prints [3, 5]
 </pre>
-** del(n[1] is like .pop in that it will remove the item at the given index, but it won't return it:
+* del(n[1] is like .pop in that it will remove the item at the given index, but it won't return it:
 <pre>
 del(n[1])

@@ Line 11: / Line 11: @@
 <pre>
 .isalpha()	# Check if alpha characters
-<pre>
+</pre>
 * Create a function
 <pre>

@@ Line 1: / Line 1: @@
-* Comment
+* Single-line comment
 <pre>
 # Hello World
 </pre>
-** Multiple-line comment
+* Multiple-line comment
 <pre>
 """"Hello