Project: survey the room

Look in eight directions, store the survey as records, report on it and head for open space.

F3.8Strings, lists and recordsGCSE25 min

Before a robot can plan a route, it has to know what is around it. In this project BugBot does a survey: it turns on the spot, looks in eight directions, stores every look as a record in a list, and then reports on its data like a scientist, before driving off towards the most open space. It brings together the whole of F3: strings, lists, records and the loop patterns.

The brief

Standing still, the robot looks in 8 directions, 45 degrees apart. For each direction it stores a record with the direction in degrees and the distance ahead. After the survey it prints a table of the records, then a report: the nearest and farthest directions, the average distance, and how many directions are open (more than 40 cm of room). Finally it turns to face the farthest direction and plays a note.

Plan the data first

Decide what one record looks like before writing any loops:

{"direction": 45, "distance": 42.0}

The survey is a list of 8 of these. Every question in the report is then a loop over that list.

Step 1: collect the survey

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

survey = []
for i in range(8):
    survey.append({"direction": i * 45, "distance": distance()})
    turn_right(30, angle=45)

for r in survey:
    print(r)

Run this in the simulator

Check the printout: eight records, directions 0 to 315. The robot turned all the way round, so it faces the way it started.

Step 2: a table

Print one line per record, with the numbers lined up. An f-string can set a width: {r['distance']:6} uses at least six characters.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

survey = [{"direction": 0, "distance": 31.0}, {"direction": 45, "distance": 42.5}, {"direction": 90, "distance": 51.0}]
print("direction  distance")
for r in survey:
    print(f"{r['direction']:9}  {r['distance']:8}")

Run this in the simulator

This cell uses a short made-up survey, so you can get the table right without waiting for the robot to turn.

Step 3: the report

Write each report line as its own small loop over survey, testing each on the made-up survey first. Then put steps 1 to 3 together in the task, and finish with the turn and the note.

Test with data you can check

Before trusting the report, work one out by hand. For the made-up survey above: the nearest is direction 0 at 31.0 cm, the farthest is direction 90 at 51.0 cm, the average is 41.5 cm, and two directions are open. If your program says something else, trace it.

Task: survey the room

Do the survey from the brief. Print the table, then exactly these report lines (your numbers will differ):

nearest: 180 degrees, 15.0 cm
farthest: 90 degrees, 51.0 cm
average: 32.4 cm
open directions: 3

Then turn to face the farthest direction and play a note.

# the two lines every program starts with: the commands, then the robot
from bugbot import *
connect()

survey = []
for i in range(8):
    turn_right(30, angle=45)

Challenges

1. Add a field open to each record, True or False, and use it for the count.
2. Round the average to one decimal place, and print the table with a line of dashes under the heading.
3. Survey in 16 directions instead of 8. What must change, and what can stay the same?