Python Variables, Data Types & Dosage Solvers (BP101T)

01

Variables & Dynamic Typing in Python

Think of a Variable in Python like a labeled container or prescription tag in a pharmacy. The tag gives a name (e.g. tablet_count), and inside is the value stored in memory (e.g. 100).

Key Features of Variables

Dynamic Typing: You don't need to specify whether a variable is a number or text in advance. Python detects the data type automatically from the assigned value.
Reassignable: A variable can hold a number initially (stock = 100) and later be updated to text (stock = "Out of Stock").
Multiple Assignment: You can set multiple variables at once: drug, dose, unit = "Paracetamol", 500, "mg".
Memory Address: Every variable points to a location in memory. You can check this unique memory ID using id(var).

PEP-8 Identifier Naming Rules

Rule	Valid Examples (✔)	Invalid Examples (❌) & Reason
Starting Character	dose, _patient_id, Age	1st_dose (Cannot begin with a number)
Allowed Characters	tablet_weight_mg, batch2026	dose-mg, price$ (No hyphens or special symbols)
Case-Sensitivity	dose, Dose, DOSE (3 separate variables)	Mixing upper and lower case causes a NameError
Reserved Keywords	patient_class, is_pass	def, class, if, import (Reserved Python words)

# Storing different values in variables

drug_name = "Amoxicillin" # String (text)

strength_mg = 500 # Integer (whole number)

half_life_hr = 1.2 # Float (decimal number)

is_approved = True # Boolean (True/False)

morning_dose, evening_dose = 250.0, 250.0 # Multiple

02

Primitive Data Types in Python

A Data Type tells Python what kind of value a variable holds and what operations can be performed on it. Python provides 4 core basic types:

Data Type	Python Class	Description	Pharmacy Examples
Integer	int	Whole numbers without any decimal point (positive, negative, or zero).	tablets = 30, patient_age = 8
Float	float	Numbers with decimal points or scientific notation.	plasma_ph = 7.41, elimination_rate = 0.045
String	str	Text characters enclosed in single (`'...'`) or double (`"..."`) quotes.	drug = "Ciprofloxacin"
Boolean	bool	Logical values representing only True or False.	is_sterile = True, is_expired = False

Checking Data Types

Use type() to inspect the data type, and isinstance(variable, type) to check if a variable matches an expected type:

dose = 250

ph = 6.8

print(type(dose)) # <class 'int'>

print(isinstance(ph, float)) # True

03

Type Casting (Type Conversion)

Type Casting means converting a value from one data type into another. This is especially important in pharmacy programs because all data entered by users via keyboard starts as text (str) and must be converted to numbers before performing calculations.

1. Automatic Conversion (Implicit Casting)

Python automatically promotes narrower types to wider types without precision loss (e.g. 500 + 0.5 = 500.5).

2. Manual Conversion (Explicit Casting)

Programmer manually converts types using: int(), float(), str(), bool().

# Explicit Type Casting in Dosage Computation

raw_dose = "125.5" # str

dose = float(raw_dose) # 125.5 (float)

full_strips = int(3.95) # 3 (Cuts off decimal without rounding)

04

Basic Operators in Python

1. Arithmetic Operators (Math Calculations)

Operator	Meaning	Example	Result	Pharmacy Scenario
+	Addition	250 + 250	500	Combining ingredients
-	Subtraction	100 - 15.5	84.5	Loss on Drying (LOD) analysis
*	Multiplication	15 * 3	45	Total tablets for a 15-day course
/	Float Division	500 / 2	250.0	Dividing a daily dose into two halves
//	Floor Division	100 // 14	7	How many complete 14-tablet blister strips can be made from 100 tablets
%	Modulus (Remainder)	100 % 14	2	Remaining loose tablets left over after packaging full strips
**	Exponent (Power)	2 ** 4	16	Pharmacokinetic decay formulas (2^4)

2. Comparison & Logical Operators

Comparison (==, !=, >, <, >=, <=): Compares two values and produces a True or False result.
Logical and: True only if both conditions are met (conc >= 10.0 and conc <= 20.0 checks if the drug is inside the therapeutic window).
Logical or: True if at least one condition is met (temp < 2.0 or temp > 8.0 triggers a cold-chain storage alarm).
Logical not: Inverts the result (not is_expired).

05

Input & Output Operations (print, input, f-strings)

Programs interact with users by taking input through the keyboard with input() and displaying results with print() and modern f-strings:

Formatting Task	f-string Syntax	Example Output
2 Decimal Places (Dosage / mg)	f"{dose:.2f} mg"	166.67 mg
Scientific / PK Notation	f"{ke:.3e}"	4.500e-02
Percentage Display	f"{purity:.1%}"	99.4%
Column Width Alignment	f"{drug:<15} {dose:>8.1f} mg"	Paracetamol 500.0 mg

06

Basic String Operations & Manipulation Techniques

A String (str) is an ordered sequence of text characters enclosed in quotes. In pharmaceutical programming, strings handle patient records, drug names, batch codes, and raw CSV files.

1. String Indexing & Slicing

Operation	Syntax	Example (`drug = "Paracetamol"`)	Result
First Letter	string[0]	drug[0]	'P'
Last Letter	string[-1]	drug[-1]	'l'
Substring Slice	string[0:4]	drug[0:4]	'Para'
Reverse String	string[::-1]	drug[::-1]	'lometacaraP'

2. Essential String Methods for Pharmacy Data

Method	Description	Example	Cleaned Output
.strip()	Removes leading and trailing spaces	" Paracetamol ".strip()	"Paracetamol"
.upper() / .lower()	Converts text to uppercase or lowercase	"amoxicillin".upper()	"AMOXICILLIN"
.replace()	Replaces substring or outdated batch code	"LOT-2024".replace("2024", "2026")	"LOT-2026"
.split(",")	Splits raw text line into a list by comma	"Aspirin,100mg".split(",")	['Aspirin', '100mg']

# Cleaning and Parsing Hospital Prescription Data

raw_drug = " amoxicillin 500mg "

clean_drug = raw_drug.strip().title() # 'Amoxicillin 500Mg'

name, strength = "Paracetamol,500mg".split(",")

07

Standard & Third-Party Libraries (Installing with pip)

A Module or Library is a collection of pre-written functions that you can import into your code, saving you from writing mathematical or statistical tools from scratch.

1. Built-in Standard Libraries

Module	Key Functions	Pharmacy Use Case
math	math.sqrt(), math.exp(), math.log()	Elimination half-life and decay equations
statistics	statistics.mean(), statistics.stdev()	Tablet weight variation and assay limits
datetime	datetime.date(), datetime.timedelta()	Shelf-life calculation and medicine expiry dates

2. Package Management with pip

Task	Terminal Command	Description
Install Package	pip install pandas matplotlib	Installs Pandas and Matplotlib from PyPI
Upgrade Package	pip install --upgrade pandas	Updates package to newest release
List Installed	pip list	Shows all installed libraries
Uninstall Package	pip uninstall pandas -y	Removes the specified library

LAB

Solved Practical: Young's Pediatric Dosage Rule

Young's Formula: Child Dose = (Age / (Age + 12)) * Adult Dose

youngs_dosage_solver.py

# B.Pharm BP101T Practical Lab: Young's Rule Solver

def calculate_pediatric_dose():
    print("--- Young's Rule Pediatric Dosage Calculator ---")
    
    # Taking inputs from user
    drug_name = input("Enter Drug Name (e.g. Paracetamol): ")
    adult_dose = float(input("Enter Adult Dose in mg: "))
    child_age = int(input("Enter Child Age in Years (1-12): "))
    
    # Young's Rule Formula
    child_dose = (child_age / (child_age + 12)) * adult_dose
    
    # Displaying Result
    print(f"\nDrug Prescribed: {drug_name}")
    print(f"Adult Dose     : {adult_dose} mg")
    print(f"Child Dose     : {child_dose:.2f} mg")

if __name__ == "__main__":
    calculate_pediatric_dose()