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* Data Types
*** Outline
***** Introduction
******* What are we going to do?
******* How are we going to do?
******* Arsenal Required
********* None
*** Script
Welcome friends.
In this tutorial we shall look at data types in Python and
mathematical operators available.
For 'Numbers' we have: int, float, complex datatypes
For conditional statements, 'Booleans'.
Lets get started by opening IPython interpreter.
Lets start with 'numbers'
All integers irrespective of how big they are of 'int' data
type. Now we will create a variable, say
x = 13
print x
To check the data type of any variable Python provides 'type' function
type(x)
lets create one more variable
y = 999999999999
(what about large value? and it is Long and not int, should we mention
that?)
print y
Floating point numbers come under 'float'
p = 3.141592
type(p)
Python by default provides support for complex numbers.
c = 3+4j
creates a complex number c. Here 'j' is used to specify the imaginary
part.
type(c)
Python also provides basic functions for their manipulations like
abs(c) will return the absolute value of c(sqrt(a^2 + b^2))
c.imag returns imaginary part and c.real gives the real part.
All the basic operators work with Python data types, without any
surprises. When we try to add two numbers like x and y Python takes
cares of returning 'right' answer and we dont have to worry about
boundary conditions.
x + y
% operator is for modulo operations
1786 % 12 gives 10
45 % 2 returns 1
Same as additions multiplication also works just right:
3124 * 126789
396088836
x ** y returns x raised to power y. For example lets try:
big = 1234567891234567890 ** 3
Division in Python truncates, that is, when we divide a integer
variable with another integer result is also integer and decimal
value is truncated. So
17 / 2 returns 8 and not 8.5
but
17 / 2.0 will return the correct 8.5, similarly
17.0 / 2 will also give correct answer.
Other operators which comes handy are:
+=
lets create one variable a with
a = 7546
now
a += 1 will increment the value of 'a' by 1
similarly
a -= 1 will decrement.
we can also use
a *= 2
a
answer is multiplied by 2
a /= 5
a is divided by 5
Next we will look at Boolean datatype:
Its a primitive datatype having one of two values: True or False.
t = True
print t
Python is case sensitive language, so True with 'T' is boolean type but
true with 't' would be a variable.
f = not True
we can do binary operation like 'or', 'and', 'not' with these variables
f or t
f and t
in case of multiple binary operations to make sure of precedence use
'brackets ()'
a = False
b = True
c = True
(a and b) or c
True
first a and b is evaluated and then the 'or' statement
a and (b or c)
False
We also have support for relational and logical operators. Lets try some
examples:
We start with initializing three variables by:
p, z, n = 1, 0, -1
To check equivalency of two variables use '=='
p == z
False
p >= n
True
We can check for multiple logical operations in one statement itself.
n < z < p
True.
This statement checks if 'z' is smaller then 'p' and greater then 'n'
For inequality testing we use '!'
p + n != z will add 'p' and 'n' and check the equivalency with z
We have already covered briefly in some of the previous sessions,
conversion of data among different types.
int(17 / 2.0) will convert result to integer type and we get
8 as answer and not 8.5
But if we try something like
float(17 / 2) we get 8.0 as 17/2 is already truncated to int
and converting that to float wont restore the lost decimal digits.
To rounding off a floating number to a given precision 'round' function
can be used.
round(7.5) returns
8.
This brings us to the end of tutorial on introduction of Data types
related to numbers in Python. In this tutorial we have learnt what are
supported data types for numbers, operations and operators and how to
convert one data type to other. Thank you!
*** Notes
|
