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F3.8 Project: survey the room

Strings, lists and records · GCSE · about 25 min

BugBotLab

What this lesson is about

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

Questions 4 marks in all

  1. [1 mark]Why plan what one record looks like before writing the survey loop?

    1. AEvery later loop depends on the fields the records have
    2. BPython needs records declared first
    3. CIt makes the robot turn faster
    4. DRecords cannot be changed later
    Answer: A. The report loops all read fields, so deciding the fields first keeps the whole program consistent.

  2. [1 mark]What does this program print?

    survey = [{"direction": 0, "distance": 31.0}, {"direction": 45, "distance": 42.5}, {"direction": 90, "distance": 51.0}]
total = 0
for r in survey:
    total = total + r["distance"]
print(total / len(survey))
    Answer:
    41.5

    The distances total 124.5, and divided by 3 records that is 41.5.

  3. [1 mark]What does this program print?

    survey = [{"direction": 0, "distance": 31.0}, {"direction": 45, "distance": 42.5}, {"direction": 90, "distance": 51.0}]
open_count = 0
for r in survey:
    if r["distance"] > 40:
        open_count = open_count + 1
print(open_count)
    Answer:
    2

    42.5 and 51.0 are over 40.

  4. [1 mark]Why test the report on a small made-up survey before using the robot's data?

    1. AYou can work the right answers out by hand and compare
    2. BMade-up data is more accurate
    3. CThe robot cannot store records
    4. DIt is required by Python
    Answer: A. Test data with known answers shows whether the program is right.

The task: survey the room

Do the survey from the brief. Print the table, then report lines in exactly this shape (these are the numbers a correct program gets in this room): 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)

The hint students can ask for: Build the list of records first, then answer each question with its own pass over that list. Turn to the direction stored in the record you chose.

A solution

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

print("direction  distance")
for r in survey:
    print(f"{r['direction']:9}  {r['distance']:8}")

nearest = survey[0]
farthest = survey[0]
total = 0
open_count = 0
for r in survey:
    if r["distance"] < nearest["distance"]:
        nearest = r
    if r["distance"] > farthest["distance"]:
        farthest = r
    total = total + r["distance"]
    if r["distance"] > 40:
        open_count = open_count + 1

print(f"nearest: {nearest['direction']} degrees, {nearest['distance']} cm")
print(f"farthest: {farthest['direction']} degrees, {farthest['distance']} cm")
print(f"average: {round(total / len(survey), 1)} cm")
print("open directions:", open_count)
turn_right(30, angle=farthest["direction"])
tone(880, 0.5)

Any program that meets the task's checks is marked correct in the simulator; this is one way, not the only way.