#f. Output format
12 spaces between the first letter of “Name” and “Grade”

print("Name %12s" % "Grade")
print("123456789012345678901234567890")
>>> 
Name        Grade
123456789012345678901234567890
>>> 

The firs %10s is for “Name” right justified.
The second %10s is for “Grade” also right justified.

print("%10s%10s" % ("Name","Grade"))
print("123456789012345678901234567890")
>>> 
      Name     Grade
123456789012345678901234567890
>>> 

The number 18129.06 has to fit in 10 spaces including the decimal
period, the two decimal digits after the period and right justified.

print("%10.2f" % (400.2 * 45.3))
print("123456789012345678901234567890")
>>> 
  18129.06
123456789012345678901234567890
>>> 

The two floating point numbers has to fit in 10 spaces and right justified.

print("%10.2f%10.2f" % (400.2 * 45.3, 55*123.2))
print("123456789012345678901234567890")
>>> 
  18129.06   6776.00
123456789012345678901234567890
>>> 

Let’s make use of the for loop, the range and the output formatting:

#g. Calculating compound interest

principal = 1000.00  # starting principal
rate = 0.5           # interest rate

print ("Year %21s" % "Amount on deposit:")

## 1234123456789012345678901
## Year    Amount on deposit:

for year in range (1,11):
    amount = principal * ( 1.0 + rate ) ** year # amount = principal * ( 1 + rate )^year
    print ("%4d%21.2f" % (year,amount))         # cool format to display a table 
##   %4d    is for a number of 4 digits for variable year
##   %21.2f is for a number of 21 positions: 18 digits, a decimal period and 2 decimal places

####################################################################################
# %21.2f indicates that variable amount is printed as a float-point value with a 
# decimal point.
# The column has a total field width of 21 character positions and two digits of
# precision to the right of the decimal point; the total field width includes the 
# decimal point and the two digits to its right, hence 18 of the 21 positions appear 
# to the left of the decimal point.
####################################################################################

print("1234123456789012345678.90")

##
##Year    Amount on deposit:
##   1              1500.00
##   2              2250.00
##   3              3375.00
##   4              5062.50
##   5              7593.75
##   6             11390.62
##   7             17085.94
##   8             25628.91
##   9             38443.36
##  10             57665.04
##1234123456789012345678.90

The range function and the for loop

The range function:

###################################################################
# Mrs. Elia
# 10/25
# python 3.x
# Description: the range function
#
###################################################################

print ("This program demonstrates how to use the range function from python")

print ("range(10) creates a sequence or list of integers from 0 to 10-1 \n", list(range (10)))

This program demonstrates how to use the range function from python
range(10) creates a sequence or list of integers from 0 to (10-1)
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

print ("These are both equivalent")
print("range(0,10): ", list(range (0,10)))
print( "and range(0,10,1): ", list(range(0,10,1)))

These are both equivalent
range(0,10): [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
and range(0,10,1): [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

The for loop

a. numbers from 1 to 10 in increments of 1

###################################################################
# Mrs. Elia
# 10/25
# python 3.x
# Description: some uses of the for loop
#
#  The for loop
#
###################################################################

for counter in range (1,11):
    print ("value containded in counter is ",counter)   # counter --> 1 2 3 4 ... 10
    

value containded in counter is 1
value containded in counter is 2
value containded in counter is 3
value containded in counter is 4
value containded in counter is 5
value containded in counter is 6
value containded in counter is 7
value containded in counter is 8
value containded in counter is 9
value containded in counter is 10

b. from 10 to 2 in increments of -1 (decrement of 1)

for counter in range (10,1, -1):
    print (counter) # counter takes on the value of each item on the list

c. from 7 to 77 in steps of 7

for counter in range (7,78,7):
    print (counter)  # counter takes on the value of each item on the list

d. Summation

suma = 0
for number in range (1,11):
    suma += number
print ("The sum of all integers from 1 to 10 is ", suma)

The sum of all integers from 1 to 10 is 55

e. Summation

suma = 0
for number in range (2,101,2):
    suma += number
print ("The sum of all even integers from 2 to 100 is ", suma)

The sum of all even integers from 2 to 100 is 2550

Python Data Structures

Assignment: Write a program, factorial_YI.py. Use the “for” loop to calculate the factorial of a given number. Prompt the user for a number. (Look for the post)

More on The Random Module

Write a program, random_module_YI.py with this short program to understand how random.randrange works.

# Show the randrange range with the "while" loop

import random

i = 0
counter1 = 0
counter8 = 0

print("This program is silently counting the number of times")
print("the numbers 1 and 8 randomly come up with the following ")
print("instruction: randNumber = random.randrange(1,8)") 


while i < 1000:
    i += 1
    randNumber = random.randrange(1,8)
    if randNumber == 1:
            counter1 += 1
    if randNumber == 8:
            counter8 += 1

print("\nThe number 1 showed up ", counter1, " number of times")
print("The number 8 showed up ", counter8, " number of times")


>>> 
This program is silently counting the number of times
the numbers 1 and 8 randomly come up with the following 
instruction: randNumber = random.randrange(1,8)

The number 1 showed up  141  number of times
The number 8 showed up  0  number of times

Answer these questions on the corresponding post:
1. What is needed to import to be able to use the randrange function?
2. What does the body of the loop do?
3. What are the two “arguments” used in randrange?
3. What can you say about the second “argument” in randrange

Assignment:
Write a program, one_die_YI.py that prompts the user how many times to roll a six-sided die and a number on the die. Then it displays how many times the numbers come up.

The output should look like this:

>>> 
User friendly introduction... 

How many times do you want to roll a six-sided die? 500
What number would you like to know how many times it comes up? 3
The number  3  showed up  61  number of times in  500  of rolls

User friendly exit ... 
>>> 

Assignment:
Write a program, one_die_all_YI.py that prompts the user how many times to roll a six-sided die. Then it displays how many times all the numbers come up.
How many times should a die be rolled to validate the theoretical probability for each face to come up?