This document is an introduction to Python programming presented in two parts. Part 1 covers basic Python concepts like data types, strings, lists, dictionaries, if/for statements and writing simple programs to print messages. It provides examples and encourages the reader to write their own small programs. The learning outcomes are listed as understanding Python basics, different statement types and completing simple programs. This introduction aims to teach Python fundamentals in an accessible way through examples and hands-on exercises.

1. INTRODUCTION TO PYTHON
PART 1 OF 2
Silvia Tinena Coris
Electronics & Automation Course Leader

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Table of contents
Part 1:
 1. Learning Outcomes
 2. Introduction
 3. The first program: hello world!
 4. The second program: hello (your name)!
 5. More data types
 6. Important things to know
 7. If Statement
 8. The third program: boy or girl?
 9. For Statement
 10. The fourth and fifth programs: your name + hello
students!
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Table of contents
Part 2:
 11. While Statement
 12. The sixth program: security word
 13. Functions
 14. Seventh program: my functions
 15. Interesting links
 16. Exercises
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4. 1. Learning Outcomes4

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Learning Outcomes
 State the basis of Python programming
 Discover the data types
 Learn the different types of statements
 Do some simple programs
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6. 2. Introduction6

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Why Python?
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 Easy to learn
 Powerful programming language
 Efficient high-level data structures
 Simple but effective approach to object-
oriented programming
 Elegant syntax and dynamic typing

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How to use Python?
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 From the shell or from the saved programs.
 The shell executes each instruction as you type it
 Useful for experiments
 Each line starts with three chevron: >>>
 The saved programs are executed all at once.
 If something isn’t correct, an error line will appear
in red explaining which kind of mistake it is and
where it is

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How to get Python?
 From a PC, downloadable for free in the
official website:
 https://www.python.org/downloads/
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How to get Python?
 From Raspberry Pi, it is already downloaded
and ready to use in the desktop (IDLE or IDLE
3)
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Comments
 They start with a hash character (#)
 They finish at the end of the line
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Numbers
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 int: signed integer numbers
 long: long integers (can also be represented in
octal or hex)
 float: real numbers, fractional part, floating point
 complex: complex numbers (j for the imaginary
part)

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Numbers
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 0x  indicates hexadecimal
 L, l  indicates long integer
 It is better to write an uppercase L to avoid
confusion with the number 1

14. 3. The first program: hello world!14

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First steps
 Open the IDLE
 File / New File
 Write your code on the new window!
 Save it
 Save before running the program (ctrl + s)
 If not, it will ask you to save it. Always say yes!
 To run: Run / Run Module or F5
 Be careful!!! Python is case
sensitive
 To interrupt the program: ctrl+c
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Hello world!
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Hello world!
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18. 4. The second program: hello
(your name)!
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Hello (your name)!
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Now, try it yourself!
Create a questionnaire and swap places with
your classmates to see who has the best one

20. 5. More data types20

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Strings
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 Contiguous set of characters in between quotation marks,
which can be simple (‘ ‘) or double (“ “)
 Accessing a single positing of a string:
 String[n]
 Where n is the desired position
 Accessing more than one position in a string:
 String[0:2]
 Take the positions 0 and 1 of the string
 The first number is included
 The second isn’t!!
 Remember: the first position is included, the last isn’t

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Strings
 Accessing more than one position in a string:
 String[:2]
 Take the first two positions
 If there is no number  0, from the beginning
 String[2:]
 Take from the second position to the end
 If there is no number  the end
 +  concatenation
 *  repetition
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Strings
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Now, try it yourself!
Create a string and play with it

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Lists
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 Enclosed within square brackets ([ ])
 Separated by commas (,)
 It is possible to have different types of data
within the same string
 They can be accessed as the strings

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Lists
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Now, try it yourself!
Create a list (or two) and
play with them

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Tuples
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 Similar to lists, but tuples CAN’T BE
MODIFIED
 “Only-read list”
 Enclosed within parentheses ( ( ) )
 Separated by commas

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Tuples
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Modifying Lists
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Now, try it yourself!
Take the lists that you’ve just created
and modify some elements

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Dictionary
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 Enclosed within curly brackets ({ })
 Separated by commas (,)
 It is possible to have different types of data
within the same dictionary
 Function (variable) in (dictionary)
 It tells us whether the variable is in the dictionary
(True) or not (False)

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Dictionary – level 1
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Now, try it yourself!
Create your own shopping list

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Dictionary – level 2
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Now, try it yourself!
Create your own
personalised messages for
checking the items on your
shopping list

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Dictionary – level 3
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Now, try it
yourself!
Swap places with
your classmates
and see who
gets the highest
score

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Converting types
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int(x [,base])
Converts x to an integer. base specifies the base if x
is a string.
long(x [,base] )
Converts x to a long integer. base specifies the base
if x is a string.
float(x) Converts x to a floating-point number.
complex(real [,imag]) Creates a complex number.
str(x) Converts object x to a string representation.
tuple(s) Converts s to a tuple.
list(s) Converts s to a list.
hex(x) Converts an integer to a hexadecimal string.
oct(x) Converts an integer to an octal string.

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Calculator
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 +
 - will return the same type of number
 * if one is float, then the result will be float
 / will always return a float (decimals)
 // forces a floor division (no decimals) – div
 % calculates the remainder – mod

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Calculator
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Float
Integer
Now, try it
yourself!
Do some
Maths
directly on
the Shell

36. 6. Important things to know36

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Important things to know
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 Declaration:=
 Used to define the value of a variable or a constant
 Comparison: ==
 Used to compare one variable or constant with a value
 It appears in statements such as if and while
 print (…) parentheses needed!
 len(string) it gives you the length of a string
 help(topic) it opens the help menu about the topic
 No need for semicolon at the end of the sentences!
 Key words in lowercase!

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Important things to know
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 Identifiers:
 Must start with a letter or an underscore
 Punctuation characters, @, $, £, %, etc. are not
allowed
 n
 It creates a line break
 You can write as many as you want together to create
more than one blank line.
 eg. nnn would create 3 blank lines
 True and False (Boolean) must have the first letter
upper-case! If so, they should be red (automatic)

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Important things to know
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 If we don’t want to end the program until the
user has pressed the enter key:
 input(‘Press the enter key to exit’)
 (Yes, it has to be the enter key)
 If you are printing strings and numbers in the
same line (the same print statement), you
should convert the numbers to string using the
function str()
 print(‘Your favourite number is
‘+str(favnumber))

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Important things to know
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 If we need that a string occupies more than
one line, start it with triple quotes (‘‘‘ ’’’) or (“““
”””)
 If a string has to contain an apostrophe (‘), it
should be written with a backslash before it to
avoid Python interpreting it as the end of the
string
 eg. print(‘They aren’t studying hard
enough.)

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Coding Styles
 Use 4-space indentation, and no tabs.
 Wrap lines so that they don’t exceed 79
characters.
 Use blank lines to separate functions and classes,
and larger blocks of code inside functions.
 When possible, put comments on a line of their
own.
 Use spaces around operators and after commas,
but not directly inside bracketing constructs:
 a = f(1, 2) + g(3, 4)
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Common Mistakes
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 Double check that:
 The indentation of all loops is correct
 The blank spaces ( ) are where they should be
 Extra spaces may lead into errors
 All brackets are closed
 When editing the code, whichever is enclosed in the
brackets will be momentary highlighted in grey
 You have colons (:) after statement words
 The spelling of the variables, functions and
constants is the same throughout all the code
 Remember that Python is very sensitive!

43. 7. If Statement43

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if
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if (condition 1):
Action 1
if (condition 1):
Action 1
else:
Action 2
if (condition 1):
Action 1
elif (condition 2):
Action 2
elif (condition 3):
Action 3

45. 8. The third program: boy or girl?45

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Boy or girl? – version 1
We need to convert the input to an integer!
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Now, try it yourself!
Create your own personalised
messages and options

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Boy or girl? – version 1
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Boy or girl? – version 2
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Now, try it yourself!
Create your own
personalised messages

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Boy or girl? – version 2.2
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Now, try it yourself!
Create your own personalised messages
with different options and different
questions

50. 9. For and Range Statements50

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For
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 In other programming languages, for is used
to iterate a sequence over certain conditions
defined by the user… but not in Python!
 In Python, it iterates over the items of any
sequence (a list or a string), in the order that
they appear in the sequence.
for (i) in (string):
…

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For
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Now, try it yourself!
Create your own list and
iterate on it to print all of its
elements on separate lines
Why not trying adding
something after each word?

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Range
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 Is like the for function in other programming
languages
for (i) in range(n):
…
 Remember that Python works with 0 as
the first element! Now, try it
yourself!

54. 10. Fourth and fifth programs:
your name + hello students
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Your name in different lines
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Now, try it yourself!
Create your own question
and iterate it

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Hello students
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Now, try it yourself!
Create your own list and
iterate on it to print all of its
elements on separate lines
with a message

57. Now go to Part 257