Pythonbasics

08 Jan 2022 - [ python  ]

BASICS Problem Solving!

When I was starting, my initial thinking was to jump in to know the syntax and memorize all the things/gotcha that I should know in a programming/scripting language. But I was wrong, first is to understand the problem that I need to solve. Of course syntax are important but understanding the problem is very important to learn before jumping into coding

tips

1. Gather as much information:
   • Learn the issue well (clear description of the problem)
   • The required Input and expected Output
   • Try brute force
2. Root cause (if any)
3. check if there is any workaround/alternatives or someone have solved it (if any)

Once the problem is understood:

1. Draw it in a piece of paper. Think of a flow chart
2. express it in words on how will the script work. (like a cookbook recipe)

With that here are the basics of Python.

Python Data Types

Variables

x = 10
name = "Amy"
pi = 3.14

Remember: Variable names must start with a letter or underscore and cannot be Python keywords (like if, for).

Arithmetic Operations

print(3 + 4)
print(10 % 3)
print(2 ** 4)

Remember: Use // for integer division, and / for float division.

Strings

name = "Alice"
print("Hello, " + name)
print(f"Hello, {name}")
print("Length:", len(name))

word = "Python"
print(word[0])     # P
print(word[-1])    # n
print(word[0:2])   # Py

Lists

fruits = ["apple", "banana", "cherry"]
print(fruits[1])         # banana
fruits.append("date")    # add item
fruits.remove("apple")   # remove item

Remember: Use append() to add, pop() to remove by index, or remove() by value.

Dictionaries

person = {"name": "John", "age": 30}
print(person["name"])
person["age"] = 31
person["job"] = "Engineer"

Remember: Keys must be unique. They’re usually strings or numbers.

Conditionals

age = 18
if age >= 18:
    print("Adult")
elif age > 12:
    print("Teenager")
else:
    print("Child")

Remember: Indentation is mandatory in Python. Use and, or, not for logic.

Boolean Logic

is_raining = True
is_cold = False

if is_raining and not is_cold:
    print("Take umbrella, no coat.")

None

result = None
if result is None:
    print("No result yet.")

Type Checking and Conversion

x = "123"
print(type(x))         # <class 'str'>
y = int(x)
print(type(y))         # <class 'int'>

Final Tips

• Use type() to check the data type.
• Use print() to debug.
• Explore with dir() and help().

print(dir(str))
help(str.upper)

Quick Summary