Python workshop

PYTHON 2.7.3
Jibin Sabu
jibinsabu@ieee.org
+918129778871

What is Python?
Python is an easy to learn, powerful programming language. It has efficient high-level data
structures and a simple but effective approach to object-oriented programming. Python’s
elegant syntax and dynamic typing, together with its interpreted nature, make it an ideal
language for scripting and rapid application development in many areas on most platforms.The
Python interpreter and the extensive standard library are freely available in source or binary
form for all major platforms from the Python Web site,http://www.python.org/, and may be
freely distributed. The same site also contains distributions of and pointers to many free third
party Python modules, programs and tools, and additional documentation.
Objective of the Workshop:
To make you able to read and write Python modules and programs, and also make you ready
to learn more about the various Python library modules described in The Python Standard
Library.

Start
->start a new terminal
->type “python”
it will display the version of python installed in
your system

-> you can start your programming
in python here (>>>)

Happy programming!!!

Comments in python
Comments in Python start with the hash
character, #, and extend to the end of the
physical line. A comment may appear at
the start of a line or following whitespace
or code, but not within a string literal. A
hash character within a string literal is just
a hash character. Since comments are to
clarify code and are not interpreted by
Python, they may be omitted when typing
in examples.

Numbers
-> The interpreter acts just as a
calculator. you can enter the
numbers and do math.
->”=” is used to assign a variable.
-> if both numbers are given as int
data type, ie by default. the resultant
will also be int
therefore n/m=2.
->if any number is of float type, the
resultant will be float type
->variable must be assigned before
using, else error occurs
->we can also have multiple variable
assignments.

complex numbers
->Complex numbers are also supported;
imaginary numbers are written with a suffix
of j or J. Complex numbers with a nonzero
real component are written as(real+imag j
), or can be created with the
complex(real, imag) function.
->Complex numbers are always
represented as two floating point numbers,
the real and imaginary part. To extract
these parts from a complex number z, use
z.real and z.imag.
->abs gives the absolute value.
->Can’t convert complex to other data type
using functions like float(z) etc.

Result of prev. calc
->In interactive mode, the last printed
expression is assigned to the variable
_. This means that when you are
using Python as a desk calculator, it
is somewhat easier to continue
calculations.
->round(n,m) function is used to
round a number n, to m decimal
places

Strings
-> They can be enclosed in single quotes
or double quotes
-> easy merging of lines.
-> easy concatenation

string.... contd
Strings can be subscripted (indexed); like in C, the first character of a string has subscript (index) 0. There
is no separate character type; a character is simply a string of size one. Like in Icon, substrings can be
specified with the slice notation: two indices separated by a colon.Slice indices have useful defaults; an
omitted first index defaults to zero, an omitted second index defaults to the size of the string being sliced.
Unlike a C string, Python strings cannot be changed. Assigning to an indexed position in the string results
in an error:However, creating a new string with the combined content is easy and efficient:Here’s a useful
invariant of slice operations: s[:i] + s[i:] equals s.Degenerate slice indices are handled gracefully: an index
that is too large is replaced by the string size, an upper bound smaller than the lower bound returns an
empty string.Indices may be negative numbers, to start counting from the right. But note that -0 is really
the same as 0, so it does not count from the right!
Out-of-range negative slice indices are truncated, but don’t try this for single-element (non-slice) indices:

List
->Python knows a number of compound data
types, used to group together other values. The
most versatile is the list, which can be written as
a list of comma-separated values (items)
between square brackets. List items need not all
have the same type.
->Like string indices, list indices start at 0, and
lists can be sliced, concatenated and so on:
->Unlike strings, which are immutable, it is
possible to change individual elements of a list:
->Assignment to slices is also possible, and this
can even change the size of the list or clear it
entirely:
->The built-in function len() also applies to lists:

First Steps Towards Programming

Fibonacci series
-> The number will be the sum of the previous two number’s.
initialise first two numbers as 0,1.
The while loop executes as long as the condition (here: b < 10) remains true. In Python,
like in C, any non-zero integer value is true; zero is false. The condition may also be a
string or list value, in fact any sequence; anything with a non-zero length is true, empty
sequences are false. The test used in the example is a simple comparison. The standard
comparison operators are written the same as in C: < (less than), > (greater than), ==
(equal to), <=(less than or equal to), >= (greater than or equal to) and != (not equal to).

Program

try without ;
trailing , avoids new line

Python workshop

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