The Dice Roller

Roll as many dice as you like; the program tallies every result and draws a little bar chart out of # marks. A loop, the random module, and a first honest taste of data — generated, counted, and displayed.

The program

import random
 
count = int(input("How many dice should I roll? "))
tally = [0, 0, 0, 0, 0, 0]
 
for roll in range(count):
    result = random.randint(1, 6)
    tally[result - 1] = tally[result - 1] + 1
 
print()
print("Results of", count, "rolls:")
 
for face in range(1, 7):
    times = tally[face - 1]
    print(face, ":", "#" * times, "-", times)

Read it before you run it

Predict in writing first — then run the program and grade yourself.

• tally is a list of six counters. Why does the program say result - 1 — what goes wrong without the - 1?
• Predict the exact output for 0 dice. (Yes, zero. Trace it.)
• Now imagine 600 dice. Roughly what should the six bars look like — and what would a wildly uneven chart suggest about the dice?

Make it yours

1. One line. Change the # bar into a character you like better.
2. A few lines. After the chart, announce which face came up most often — a loop over the tally will find it.
3. A real change. Roll two dice each round and tally the sums from 2 to 12. Run it big, look at the shape of the chart, and explain why 7 turns out to be the celebrity.

Curriculum connection

C1.4

determine the appropriate expressions and instructions to use in a programming statement, taking into account the order of operations

Link to original

C2.2

write programs that use and generate data involving various sources and formats

Link to original

C3.1

analyze existing code to understand the components and outcomes of the code

Link to original

C3.4

write programs that make use of external or add-on modules or libraries

Link to original