print()Print is pretty much the same as echo in Bash and PHP and puts in Ruby
1name = "Aamnah Akram"
2print(name)
input()Function to get information from a user. Always gets a string, even if the content is a number.
1input("How are you today?")
Variables in Python can not start with a number
1name = "Aamnah"
Save input as variable
1name = input("What is your name? ")
2print(name)
1if name == "Aamnah":
2 print(name + " is awesome!")
3else:
4 print(name + " is OK i guess. " + name " is fine!")
Your if statement will work with or without the parentheses ( ) but since 2010, the style guide recommends using them. So if (name == "Aamnah"): is preferred over if name == "Aamnah":
or and andHere is an example
1#!/bin/python
2
3answer = raw_input("Are you a dumbo? YES or NO ")
4
5if (answer == 'yes') or (answer == 'y'):
6 print("Of course you are! You're very honest. ")
7
8else:
9 print("Lier Lier! ")
will output ‘Of course you are! You’re very honest.’ if you answer with y or yes. If you answer with anything else, it’ll say Lier Lier!
1name = input("What's your name? ")
2age = input("What's your age? ")
3print(name + " is " + age " years old.")
1name = input("What's your name? ")
2if name == "Aamnah":
3 print("{} is awesome".format(name))
4else:
5 print("{} is OK i guess. {} is fine!".format(name, name))
Another example
1name = "Aamnah"
2age = 25
3city = "Dubai"
4print("{} is {} years old. She lives in {}".format(name, age, city))
When you divide two numeric values, you always get a float as result. Floats work mostly how they are supposed to but occasionally you’ll find some odd problems. For example
10.1 + 0.1 + 0.1 - 0.3
should result 0 but gives 5.551115123125783e-17 instead.
1int('55')
2float('2.897')
When you take input in, it always takes it as a string. So you’d have to convert it to an int or float first in order to do any kind of calculation on it.
1int('2.2')
2float('2')
round()round() rounds a float to the nearest whole number. round(2.4) will become 2 and round(3.9) will become 4.
1user_string = "What's your word? "
2user_num = "What's your number? "
3
4try:
5 our_num = int(user_num)
6except:
7 our_num = float(user_num)
8
9if not '.' in user_num:
10 print(user_string[our_num]
11else:
12 ratio = round(len(user_string)*our_num)
13 print(user_string[ratio])
in, not inCheck if something is in or not in something else. For example, 'a' in 'Aamnah' would return True. 'b' not in 'Aamnah' would return True. 'x' in 'Aamnah' would return False
len()1>>> fruits = ['Apple', 'Bannana', 'Mango', 'Cherries', 'Guava']
2>>> len(fruits)
35
list()1>>> list('a')
2['a']
1>>> list('hello')
2['h', 'e', 'l', 'l', 'o']
1>>> fruits = ['Apple', 'Bannana', 'Mango', 'Cherries', 'Guava']
2>>> 'Apple' in fruits
3True
1>>> fruits = ['Apple', 'Bannana', 'Mango', 'Cherries', 'Guava']
2>>> 'Orange' in fruits
3False
.append()We can only add lists to other lists. .append() add to the end of a list.
.split()Calling .split() on a string breaks the string up on whitespaces. If we had Returns or Tabs, they’d also break.
1>>> sentence = "My name is Aamnah. I am curious!"
2>>> sentence.split()
3['My', 'name', 'is', 'Aamnah.', 'I', 'am', 'curious!']
.join()1>>> sentence = "My name is Aamnah. I am curious!"
2>>> sentence.split()
3['My', 'name', 'is', 'Aamnah.', 'I', 'am', 'curious!']
4>>> sentence_list = sentence.split()
5>>> ' '.join(sentence_list)
6'My name is Aamnah. I am curious!'
You can determine what is used to join the list. In the example above, we used spaces. We can also use _ or - or something else.
1>>> '_'.join(sentence_list)
2'My_name_is_Aamnah._I_am_curious!'
Everything we are joining has to be a string. We can’t join numbers.
while loops
1count = 0
2while (count < 9):
3 print 'The count is:', count
4 count = count + 1
5
6print "Good bye!"
for loops
1>>> my_list = [1, 2, 3, 4]
2>>> num my_list:
3... print(num)
41
52
63
74
See More examples
A for loop can only iterate (loop) “over” collections of things. A while loop can do any kind of iteration (looping) you want. However, while loops are harder to get right and you normally can get many things done with for loops.
else in LoopsIf the else statement is used with a for loop, the else statement is executed when the loop has exhausted iterating the list.
If the else statement is used with a while loop, the else statement is executed when the condition becomes false.
1#!/usr/bin/python
2
3count = 0
4while count < 5:
5 print count, " is less than 5"
6 count = count + 1
7else:
8 print count, " is not less than 5"
When the above code is executed, it produces the following result:
0 is less than 5
1 is less than 5
2 is less than 5
3 is less than 5
4 is less than 5
5 is not less than 5
break and continuebreak makes Python stop whatever loop it is in, which works really well with infinite loops. continue let’s us move on to the next step in the loop.
1while True
2 if new_item == 'END':
3 break
4 shopping_list.append(new_item)
5 print("Item added")
6 continue
open()open() - Opens a file in Python. This won’t contain the content of the file, it just points to it in memory.
1open("name.txt")
You can also specify encoding
1open("name.txt" encoding="utf-8")
For ease of use, save the file in a varibale
1names_file = open("name.txt" encoding="utf-8")
By open() you don’t get the actual contents of the file, you just get a pointer to the file. To get the contents, you would use read()
read()read() gets the contents of a file for you. For ease of use, you can save the content in a variable.
1data = names_file.read()
close()Once you have opened the file and read it, you should close it.
1names_file.close()
Closing the file prevents it from taking up memory.
There are loads of built-in modules available for Python. You can find a list here. You use the keyword import to bring outside libraries into your code.
You load a library/module using import
1import urllib2
2import json
3import re
You can specify multiple modules in one import statement
1import urllib2, json, re
Functions follow the same naming rules as variables. You can’t start a function name with a number and you can’t put any hyphens or special characters in the name. We use the keyword def for defining every function, like so
1>>> def say_hello():
2... print("Hello!")
3...
4>>> say_hello()
5Hello!
Taking arguments is also easy
1>>> def say_hello(name):
2... print("Hello " + name + "!")
3...
4>>> say_hello("Amna")
5Hello Amna!
Getting back data using return for when you want to get data back from a function and not just print it.
1>>> def square(num):
2... return num*num
3...
4>>> square(99)
59801
Here is an example of a shopping list with a function to add list items, another function to show help, and a function to show list.
1shopping_list = []
2
3def show_help():
4 print("What should we pick up at the store? ")
5 print("Enter DONE to stop. Enter HELP for this help. Enter SHOW to see your current list")
6
7def add_to_list(item):
8 shopping_list.append(item)
9 print("Added! List has {} items".format(len(shopping_list)))
10
11def show_list():
12 print("Here is your list:")
13 for item in shopping_list:
14 print(item)
15
16show_help()
17
18while True:
19 new_item = raw.input("> ")
20 if new_item == 'DONE':
21 break
22
23 elif new_item == 'HELP':
24 show_help()
25 continue
26
27 elif new_item == 'SHOW':
28 show_list()
29 continue
30
31 add_to_list(new_item)
32 continue
33
34show_list()
Collections are variable types that collect different types of data together. They are also called iterables because you iterate or loop through them.