GPS data processing in Drone Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Calculate distance between two GPS points

What is the output of this code that calculates the distance between two GPS coordinates using the Haversine formula?

Drone Programming

import math

def haversine(lat1, lon1, lat2, lon2):
    R = 6371  # Earth radius in km
    phi1 = math.radians(lat1)
    phi2 = math.radians(lat2)
    dphi = math.radians(lat2 - lat1)
    dlambda = math.radians(lon2 - lon1)

    a = math.sin(dphi/2)**2 + math.cos(phi1)*math.cos(phi2)*math.sin(dlambda/2)**2
    c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))

    return R * c

print(round(haversine(52.2296756, 21.0122287, 41.8919300, 12.5113300), 2))

A 1150.25

B 1317.53

C 2890.12

D 980.45

💡 Hint

Remember the Haversine formula calculates great-circle distance between two points on a sphere.

The code uses the Haversine formula correctly and calculates the distance between Warsaw (52.2296756, 21.0122287) and Rome (41.8919300, 12.5113300) as approximately 1317.53 km.

🧠 Conceptual

intermediate

Understanding GPS coordinate formats

Which option correctly converts GPS coordinates from degrees, minutes, seconds (DMS) to decimal degrees?

A decimal = degrees + minutes/60 + seconds/3600

B decimal = degrees + minutes*60 + seconds*3600

C decimal = degrees * 60 + minutes + seconds/60

D decimal = degrees + minutes/3600 + seconds/60

💡 Hint

Think about how many minutes are in a degree and how many seconds are in a minute.

To convert DMS to decimal degrees, minutes are divided by 60 and seconds by 3600, then added to degrees.

🔧 Debug

advanced

Fix the GPS coordinate parsing error

What error does this code raise when parsing GPS coordinates from a string?

gps_str = "48°51'29.6\"N, 2°17'40.2\"E"
lat, lon = gps_str.split(",")
lat_deg, lat_min, lat_sec = map(float, lat[:-1].split("°"))
lon_deg, lon_min, lon_sec = map(float, lon[:-1].split("°"))

A ValueError: too many values to unpack

B AttributeError: 'float' object has no attribute 'split'

C ValueError: could not convert string to float

D IndexError: string index out of range

💡 Hint

Check how the string is split and converted to float.

The code tries to convert strings like "51'29.6\"N" directly to float, which fails because of non-numeric characters like ' and ".

📝 Syntax

advanced

Identify the syntax error in GPS data filtering

Which option contains the correct syntax to filter GPS points with latitude greater than 40 using a dictionary comprehension?

Drone Programming

gps_points = {"p1": (39.9, -75.2), "p2": (41.1, -74.9), "p3": (40.5, -73.9)}

A {k: v for k, v in gps_points.items() if v[0] => 40}

B {k: v if v[0] > 40 for k, v in gps_points.items()}

C {k: v for k, v in gps_points.items() v[0] > 40}

D {k: v for k, v in gps_points.items() if v[0] > 40}

💡 Hint

Remember the correct order of clauses in a dictionary comprehension.

Option D correctly uses 'if' after the 'for' clause. Other options have syntax errors or wrong operators.

🚀 Application

expert

Calculate average GPS speed from timestamped points

Given a list of GPS points with timestamps, which option correctly calculates the average speed in km/h between the first and last points?

points = [
    {"lat": 52.0, "lon": 21.0, "time": 0},
    {"lat": 52.1, "lon": 21.1, "time": 1800},  # 30 minutes later
    {"lat": 52.2, "lon": 21.2, "time": 3600}   # 60 minutes later
]

A

from math import radians, sin, cos, sqrt, atan2
R = 6371
p1, p2 = points[0], points[-1]
dlat = radians(p2['lat'] - p1['lat'])
dlon = radians(p2['lon'] - p1['lon'])
phi1 = radians(p1['lat'])
phi2 = radians(p2['lat'])
a = sin(dlat/2)**2 + cos(phi1)*cos(phi2)*sin(dlon/2)**2
c = 2*atan2(sqrt(a), sqrt(1-a))
distance = R * c
elapsed_hours = (p2['time'] - p1['time']) / 3600
speed = distance / elapsed_hours
print(round(speed, 2))

B

p1, p2 = points[0], points[-1]
distance = ((p2['lat'] - p1['lat'])**2 + (p2['lon'] - p1['lon'])**2)**0.5
elapsed_hours = (p2['time'] - p1['time']) / 3600
speed = distance / elapsed_hours
print(round(speed, 2))

C

from math import radians, sin, cos, sqrt, atan2
R = 6371
p1, p2 = points[0], points[-1]
dlat = radians(p2['lat'] - p1['lat'])
dlon = radians(p2['lon'] - p1['lon'])
phi1 = radians(p1['lat'])
phi2 = radians(p2['lat'])
a = sin(dlat/2)**2 + cos(phi1)*cos(phi2)*sin(dlon/2)**2
c = 2*atan2(sqrt(a), sqrt(1-a))
distance = R * c
elapsed_hours = (p2['time'] - p1['time'])
speed = distance / elapsed_hours
print(round(speed, 2))

D

from math import radians, sin, cos, sqrt, atan2
R = 6371
p1, p2 = points[0], points[-1]
dlat = radians(p2['lat'] - p1['lat'])
dlon = radians(p2['lon'] - p1['lon'])
phi1 = radians(p1['lat'])
phi2 = radians(p2['lat'])
a = sin(dlat/2)**2 + cos(phi1)*cos(phi2)*sin(dlon/2)**2
c = 2*atan2(sqrt(a), sqrt(1-a))
distance = R * c
elapsed_hours = (p2['time'] - p1['time']) / 60
speed = distance / elapsed_hours
print(round(speed, 2))

💡 Hint

Use the Haversine formula for distance and convert time difference to hours correctly.

Option A correctly calculates the great-circle distance and divides by elapsed time in hours. Option A uses Euclidean distance which is inaccurate for GPS. Option A divides time by 60 (minutes) instead of 3600 (seconds to hours). Option A uses raw seconds as hours.