Question

In Python

Trace "Stars.py" by drawing a table that shows the values of relevant variables (row and star) and keeping track of the output. This program contains a nested for loop, so for each iteration of the outer loop, the inner loop executes in its entirety:

row	star
1	1
2	1
2	2
3	1
3	2
3	3
...	...

#********************************************************************
# stars.py
#
# Demonstrates the use of nested for loops.
#********************************************************************

#-----------------------------------------------------------------
# Prints a triangle shape using asterisk (star) characters.
#-----------------------------------------------------------------

def main():
MAX_ROWS = 5

for row in range(1, MAX_ROWS + 1):
for star in range(1, row + 1):
print ('*', end = '')
  
print ('\n')

# Invoke/call main function.
main()

Answer 1

Solution :

To easily implement a tabular format for tracing outputs, we use tabulate.py library for creating a table.

Steps to install tabulate.py:

1. Open your command prompt as an administrator.

2. Type "pip install tabulate"

3. It will take a few seconds to finish.

4. Exit command prompt.

Now the code:

from tabulate import tabulate       #To import tabulate function from tabulate library
columns = ["Row", "Stars"]          #Initializing a list containing the column names for the table
output_data = []                    # List to store row elements
def main():                         # main function as given in the question
    MAX_ROWS = 5
    for row in range(1, MAX_ROWS + 1):
        for star in range(1, row + 1):
            print('*', end='')
            output_data.append(tuple((row, star)))      #To append stars and row number in the list
        print("\n")

main()                                                  #Invoking of main function
print(tabulate(output_data, headers=columns, tablefmt="grid"))      #Printing in the table format, defining table format as grid

Screenshot:

Output: