learn-python

Learn python language

Strings

Strings in Pythin can be enclosd by 'Single quotes: Pursuit of excellence' or "Double quotes: Pursuit of excellence". Strings can be escaped using backslash \ character, for example \n is newline, and \t is tab. Literal strings are enclosed within triple single-quotes or triple double-quotes. For example '''String literal''' or """String literal""". An escape in string literal means continuation of next line.

Formatted Stings

The strings can fill in variables values, e.g.:

what = 42
# use the f-string mechanism
answer = f"The answer to the Ultimate Question of Life, the Universe, and Everything is {what}."

Lists

Refers to an array. You can create a list, and append, extend or clear it.

# Create and array:
primes = []
primes.extend([2,3,5,7]) # Add 4 primes
primes.append(11) # Add another prime
primes[:] = [] # clear the list

While iterating over a list do not update the list. If you need to update the list in a loop iterate over copy.

repeat = [1, 2, 3]
for value in repeat[:]:  # repeat[:] creates a copy
    repeat.append(value)
# repeat now is [1,2,3,1,2,3]

List APIs

The Data Structures - More on lists documents all APIs. Some are:

colors = ["violet", "indigo", "blue"]

# Stack, push (append function)
colors.append("green")
colors.append("yellow")

# Pop first element
violet = colors.pop(0) # colors now is: ["indigo", "blue", "green", "green"]

# Sort 
colors.sort(reverse = True)

Control Statements

for

A for-loop is used for iterating over a list, a tuple, a dictionary, a set, or a string sequence.

squares = [1**2, 2**2, 3**2, 4**2]
# Print each value
for val in squares:
    print(f"val = {val}")

Use enumerate to get a index.

cubes = [1**3, 2**3, 3**3, 4**3]
for i, c in enumerate(cubes):
    print(f"cube[{i}]={c}")

for-loop can work with range() function.

Utilities

# Masure time of each function execution

python -m cProfile file.py

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