Variables

Topics: variable, data, values, comments

Variables are like containers that store information — think of them as labeled drawers where you can keep different kinds of data such as a patient’s name, age, or blood pressure.

In Python, you don’t have to specify what type of data a variable will hold — Python automatically figures that out for you!

Creating variables is simple.

It’s not an exaggeration that variables are going to be your friends in the long run.

patient_name = 'Maria Santos'
patient_age = 45
patient_bmi = 24.6
has_diabetes = True

print(patient_name)   # Output: Maria Santos
print(patient_age)    # Output: 45

Example context: Imagine you’re storing basic information from a patient’s medical record — each variable holds one detail about the patient.

Mini Exercise

Try It Yourself 🧠

Create three variables to store:

  • A patient’s heart rate (in beats per minute)
  • Their body temperature (in °C)
  • Whether they are currently admitted (True or False)

Then, print all three variables!

# Use your own variables and values
heart_rate = 140
body_temp = 36.4
admitted = True

# Print the results using the 'print' function
print(heart_rate)     # 140
print(body_temp)      # 36.4
print(admitted)       # True
Bonus: Comments

Comments are lines in the code that are ignored by the interpreter and serve as notes or explanations for humans reading the code. In healthcare data analysis, comments are useful when explaining what part of the data your code is processing, such as “# Calculate average blood pressure per patient” or “# Filter data for diabetic patients only”.

  • A comment starts with the ‘#’ symbol and continues to the end of the line.
  • Python also supports multi-line comments using triple quotes (‘’’ or “””), though these are technically treated as multi-line strings unless assigned or used in docstrings (used later on in the ‘Control Structures’ section).

Example:

# Store blood pressure readings of 2 patients
bp_1 = 120
bp_2 = 130

# Calculate average blood pressure
average_bp = (bp_1 + bp_2) / 2
Variable Naming Rules
  • Must start with a letter or underscore (_)
  • Avoid using a single underscore as a variable name
  • Can contain letters, numbers, and underscores
  • Case-sensitive (name and Name are different)
  • Cannot use Python keywords (like if, for, while, class, def, list, str)
  • Avoid names starting and ending with double underscores (__init__, __str__). These are reserved for special methods in Python classes
  • Use lowercase letters with underscores (snake_case) for variable names
  • Make names meaningful and specific to their purpose
  • Avoid abbreviations unless they’re widely understood (num is okay, nm is not)

💡 Pro tip: In medical or research projects, use clear, descriptive names like blood_glucose_level or patient_weight_kg. This makes your code easier for colleagues or research assistants to understand.

Variable Naming Practices

Good variable names

patient_id = 'P001'
blood_glucose_mgdl = 95
is_fasting = True

Avoid these

x = 'P001'               # Not descriptive
patientName = 'Maria'    # Should use snake_case
2patient = 'invalid'     # Cannot start with number
Introduction Basic Data Types