Python Chap 6

Random number

useful for programs like dice rolling, how animal or insect might behave, statistical analysis or security for encryption.

Module

A python file that has code in it that you call in to another python program when you run it. AKA Modularization.

Random number seeds

Actually uses system time, They are pseudo-random numbers calculated by a formula. If the same seed were always used, the same random numbers would be generated. Since time changes, the chances of having the same seed are small.

Library Functions

Are built in functions in python. The basic ones like print, input etc are built in but others like random etc are called with "import random" "import math". Must write import statement at top. It tells python the name of the module that contains the function.

Remember modulus or remainder operator

Gives you remainder but will not display float numbers. I.E 1%100 = 1 2%10 = 10 5%10 = 5 BUT 100%1 = 0 10%2 = 0 10%5 = 0 11%3 = 2 (3 x 3 = 9. Remainder 2)

Value returning function

It returns a value back to the part of the program that called it. It is a group of statements to perform a specific task. It is called by another part of the program

math.hypot

Just a built in math function to calc hypotenuse.

How to create a new txt doc in a specific location

Make sure to put the r before the location and end it with the "w" file_name = open(r"C:\Users\Roger\Dropbox\Dropbox\COSC 1336\roger.txt", "w")

Square root function

Must import math first. Then use math.sqrt I.E number = math.sqrt(5)

Random and seed relation

PG212. Random import actually imports system clock and uses that as a seed value to create a random number. The systems time is down to a hundredth of a second. Because the clock keeps changing you get different numbers, some times if you want to same number repeated and NOT be random then you call random.seed

return expression

PG214 It return a value back to the part of the program that called it. Program 6-6. Also look at pg 215 figure 6-6 def sum(num1,num2): result = num1 + num2 return result

random.random or random.uniform

These will return a floating point number not an integer.

Describe value returning functions

They simplify code, enhance team work, increase the speed of development, reduce duplication.

number = random.randrange(5, 10) number = random.randrange(0, 101, 10)

This specifies a starting limit and a ending limit. But still will not show 10. The second one starts at goes in steps of 10 from 0-100 We can use random.randrange or random.randint both return and integer.

number = random.randrange(10)

This will print number from 0-9 not including 10.

number = random.uniform(1.0 , 100.)

This will randomly display numbers as floating points between 1.0-100.0. PG212

Module File

When importing a module file it must have a .py extension

number = random.random()

Will just display a number between 0.0 and 1.0 and will be a decimal number. PG212

random

it has to be imported for Python to use the random module. use it in something like this number = random. randint(1,100) This will gen a random number from 1-100 and assign it to number. Look at ch6 random numbers 2.py

math module

its a built in math function that has to be summoned in python like "import math"

randrange

its just like the range function except it return a random number. I.E number = random.randrange (5, 10) Selects a random number from 5-9 randint and randrange return integers.

To calc the area of a circle

math.pi * radius**2. Make sure to import the import math module.