Transcript DATA TYPE - Mohd Anwar

DATA TYPE
NUMBERS
A number is an immutable type – means that
changing or updating its value result in a newly
allocated object.
 There are several types of numeric types –
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Integer
Long integer
Boolean
Double –precision floating point real numbers
Decimal floating point numbers
Complex numbers
INTEGERS
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There are several types of integers
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Boolean type – 2 possible values, True and False
Actually an integer and behave like integer values 0
and 1 if used in numeric context.
Standard Integers
Python standard integers are the universal numeric
type.
 Most machines (32-bit) running Python will provide a
range of -231 to 231 -1 ( -2,147,483,648 to 2,147,483,647)
 Example of integer : 0101, 84, -234,Ox80 etc
 Integers are normally represented in base 10 decimal
format.
 It can also be represented in base 8 (octal, “0”
prefix)or base 16 (hexadecimal, “0x”/”OX” prefixes)
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LONG INTEGERS
Longs are a superset of integers
 It is useful when your application requires
integers that exceed the range of plain /standard
integers.
 Use of longs is denoted by the letter ‘L’,
uppercase (L) or lowercase (l), appended to the
integer’s numeric values.
 Values can be expressed in decimal , octal , or
hexadecimal.
 Examples : 16384L,-Ox4E8L ,5432101234L,2997924581l
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DOUBLE PRECISION FLOATING POINT
NUMBERS
Floating point values are denoted by a decimal
point (.) in the appropriate place and an optional
“e” suffix representing scientific notation.
 Can use either lowercase (e) or uppercase (E).
 Positive (+)/negative (-) signs between the “e” and
the exponent indicate the sign of the exponent.
 No sign indicate positive exponent.
 Examples : 0.0, -5.55557119, -1.609E-19,3.67 etc
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COMPLEX NUMBERS
Combining a real number with an imaginary
number
 Example: 64.375 +1j, 0.23-8.55j,9.80665-8.31441J
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OPERATORS-NUMERIC TYPE (ARITHMETIC )
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Division
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Classic division
Using integer operands, classic division truncates the
fraction, returning an integer (floor division).
 Using a pair of floating point operands, it returns the actual
floating-point quotient (true division).
 Example :
>>> 1/2 #perform integer result (floor)
0
>>> 1.0/2.0 #returns actual quotient
0.5
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CONTINUE
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True division
the division always returns the actual quotient
regardless of the type of the operands
 For now, to take advantage of true division, need to
give the from_future_import division directive.
 Once that happens, the division operator (/) performs
only true division.
>>> from_future_import division
>>>
>>>1/2
0.5
>>>1.0/2.0
0.5
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CONTINUE
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Floor division
(//)- always truncates the fraction and rounds it to the
next smallest whole number toward the left on the
number line, regardless of the operands’ numeric
types.
Examples:
>>> 1 // 2
0
>>>1.0 // 2.0
0.0
>>>-1 // 2
-1
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MODULUS
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Integer modulus is straightforward integer
division remainder .
Exponentiation
 Has a peculiar/strange precedence rule in its
relationship with the unary operators.
 It binds more tightly than unary operators to its
left, less tightly than unary operators to its right.
 example:
>>> 3 ** 2
9
CONTINUE
>>> -3 ** 2 # perform 3 to the power of two before
applies the unary negation
-9
>>> (-3) ** 2
9
EXAMPLES OF NUMERIC OPERATORS
>>> -442 -77
-519
>>> 4**3
64
>>> 4.2 ** 3.2
98.7183139527
>>> 8/3
2
>>> 8.0/3.0
2.66666666667
>>> 8 % 3
2
CONTINUE
>>> (60. -32.) * (5./9.)
15.5555555556
>>> 14 * 0x04
56
>>> 0170/4
30
>>> 45L * 22L
990L
NUMERIC TYPE FUNCTIONS
Function
operation
bool (obj)
Returns the boolean value of obj.
int (obj,base =10)
Returns integer representing of string or
number obj.
long (obj, base =10)
Returns long representation of string or
number obj.
float (obj)
Returns floating point representation of string
or number obj
complex (str)
Returns complex number representation of str,
or builds one given real
EXAMPLES
>>> int (4.2555)
4
>>> long (42)
42L
>>> float(4)
4.0
>>>complex(4)
(4+0j)
OPERATIONAL
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Python has five operational built-in function for
numeric types:
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abs() – returns the absolute value of the given
argument. If the argument is a complex number,
then math.sqrt(num.real2 +num.imag2) is
returned.
coerce ( ) – returns a tuple containing the converted
pair of numbers.
divmod ( ) –combines division and modulus
operations into a single function.
The values returned are the same as those given for the
classic division and modulus operator for integer type.
 As for float, the quotient returned
math.floor(num1/num2).
 As for complex numbers, the quotient is
math.floor((num1/num2).real)
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CONTINUE
pow ( ) – pow () and ** perform exponentiation, one is
operator (**), and the other is build-in function.
 round ( ) – has a syntax of round(flt,ndig=0)
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rounds a floating point number to the nearest integral
number and returns that result still in a float.
 When the optional ndig is given, round () will round the
argument to the specific number of decimal places.

EXAMPLE
abs ()
>>> abs(-1)
1
>>> abs (10.)
10.0
>>> abs (0.23-0.78)
0.55

• coerce
()
>>> coerce(1,2)
(1,2)
>>>coerce (1,134L)
(1L,134L)
CONTINUE WITH EXAMPLES
>>>divmod(10,3)
(3,1)
>>> divmod (3,10)
(0,3)
>>> pow(2,5)
32
>>> round (3)
3.0
>>> round(3.49999,1)
3.5
>>> bool(1)
True
>>> bool(True)
True
>>> bool(‘1’)
True