8. Variables and Data Types#
8.1. Introduction#
8.2. Learning Objectives#
8.3. Variables in Python#
num_points = 120
print(num_points)
num_points
8.3.1. Variable Assignment#
# Start with a number
location_data = 42.3601
# Change to text
location_data = "Boston"
# Change to a list of coordinates
location_data = [42.3601, -71.0589]
print(location_data)
8.4. Naming Variables#
8.4.1. Good Naming Examples for Geospatial Data#
# Good variable names for geospatial data
latitude = 42.3601
longitude = -71.0589
elevation = 147.2
city_name = "Boston"
population = 685094
coordinate_system = "WGS 84"
8.4.2. Poor Naming Examples to Avoid#
# Poor variable names - avoid these
x = 42.3601 # Too generic
data = "Boston" # Too vague
temp = 25.6 # Ambiguous - temperature or temporary?
l = [42.36, -71.06] # Single letter variables are hard to understand
8.5. Data Types#
num_features = 500 # Represents the number of features in a geospatial dataset
latitude = 35.6895 # Represents the latitude of a point on Earth's surface
longitude = 139.6917 # Represents the longitude of a point on Earth's surface
coordinate_system = "WGS 84" # Represents a commonly used coordinate system
is_georeferenced = True # Represents whether a dataset is georeferenced or not
coordinates = [
35.6895,
139.6917,
] # A list representing latitude and longitude of a point
feature_attributes = {
"name": "Mount Fuji",
"height_meters": 3776,
"type": "Stratovolcano",
"location": [35.3606, 138.7274],
}
8.6. Escape Characters#
print("Hello World!\nThis is a Python script.")
print("This is the first line.\n\tThis is the second line. It is indented.")
print("What's your name?")
print("What's your name?")
8.8. Working with Variables and Data Types#
num_features += 20
print("Updated number of features:", num_features)
import math
latitude = 35.6895
latitude_radians = math.radians(latitude)
print("Latitude in radians:", latitude_radians)
coordinates = [35.6895, 139.6917]
coordinates.append(34.0522) # Adding latitude of Los Angeles
coordinates.append(-118.2437) # Adding longitude of Los Angeles
print("Updated coordinates:", coordinates)
mount_fuji_name = feature_attributes["name"]
mount_fuji_height = feature_attributes["height_meters"]
print(f"{mount_fuji_name} is {mount_fuji_height} meters high.")
8.9. Basic String Operations#
8.9.1. Changing Case#
city_name = "San Francisco"
# Convert to lowercase
city_lowercase = city_name.lower()
print("Lowercase:", city_lowercase)
# Convert to uppercase
city_uppercase = city_name.upper()
print("Uppercase:", city_uppercase)
# Convert to title case (first letter of each word capitalized)
city_title = city_name.title()
print("Title case:", city_title)
8.9.2. Replacing Text#
original_city = "San Francisco"
new_city = original_city.replace("San", "Los")
print("Original:", original_city)
print("Modified:", new_city)
8.9.3. Other Useful String Methods#
location_data = " Mount Everest "
# Remove whitespace from beginning and end
clean_location = location_data.strip()
print("Cleaned:", clean_location)
8.7. Comments in Python#