Contents

Python - Basics

Python

  • High−level.

  • Clean, readable, and efficient.

  • Easy and fun to learn.

  • Dynamic.

  • Fast to write and test code.

  • Less code.

  • Flexible.

  • Interactive.

  • Great support

  • Open source.

  • Vast range of libraries.

  • Huge number of users.

  • Slow (sometimes).

Data types

x = 10
type(x)

int

y = 0.5
type(y)

float

x + y

10.5

z = x / 2
z

5.0

type(z)

float

int(z)

5

my_string = 'Hello'
type(my_string)

str

print(my_string)

Hello

my_string.upper()

'HELLO'

greeting = 'Hello, I am Gary.'
greeting

'Hello, I am Gary.'

greeting.split(' ')

['Hello,', 'I', 'am', 'Gary.']

greeting.replace("Gary", "Gary's Mother")

"Hello, I am Gary's Mother."

'-'.join(greeting)

'H-e-l-l-o-,- -I- -a-m- -G-a-r-y-.'

my_list = [1, 2, 3, 4, 5]
type(my_list)

list

len(my_list)

5

my_list[0]

1

my_list[-1]

5

my_list[-1] = my_string
my_list

[1, 2, 3, 4, 'Hello']

my_list.append(x)

my_list

[1, 2, 3, 4, 'Hello', 10]

[num for num in range(10)]

[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

my_dict = {'a': 1, 'b': 2, 'c': 3}
type(my_dict)

dict

my_dict.keys()

dict_keys(['a', 'b', 'c'])

my_dict.values()

dict_values([1, 2, 3])

my_dict['b']

2

my_dict.update({'d': greeting})

my_dict

{'a': 1, 'b': 2, 'c': 3, 'd': 'Hello, I am Gary.'}

my_boolean = True
type(my_boolean)

bool

my_boolean == True

True

my_boolean == False

False

Control flow

if 10 < 20:
    print(f'Truthy')

Truthy

if True:
    print(f'Truthy')

Truthy

for num in range(5):
    print(num)

0
1
2
3
4

for num in range(5):
    if num % 2 == 0:
        print(f'{num} is even')

0 is even
2 is even
4 is even

for num in range(5):
    if num % 2 == 0:
        print(f'{num} is even')
    else:
        print(f'{num} is odd')

0 is even
1 is odd
2 is even
3 is odd
4 is even

colours = ['red', 'green', 'blue']
for index, colour in enumerate(colours):
    print(index, colour)

0 red
1 green
2 blue

my_dict = {'a': 1, 'b': 2, 'c': 3}

for key, value in my_dict.items():
    print(key, value)

a 1
b 2
c 3

Modules

import os

os.getcwd()

'/home/lukeconibear/introduction_to_scientific_computing/book'

import glob

glob.glob('*bash')

['dask_on_hpc.bash']

import re

re.findall(r'\d+', 'Hello 12345')

['12345']

Functions

def say_hello(*args): # arguments
    for arg in args:
        print(f'Hello {arg}!')

say_hello('Gary')

Hello Gary!

say_hello('Gary', "Gary's Mother")

Hello Gary!
Hello Gary's Mother!

def do_maths(x=2, y=3, z=4): # keyword arguments
    print(f'x = {x}')
    print(f'y = {y}')
    print(f'z = {z}')
    result = (x + y) * z
    print(f'result = {result}')

do_maths()

x = 2
y = 3
z = 4
result = 20

do_maths(1, 2, 3)

x = 1
y = 2
z = 3
result = 9

do_maths(3, 2, 1)

x = 3
y = 2
z = 1
result = 5

do_maths(z=3, y=2, x=1)

x = 1
y = 2
z = 3
result = 9

def do_maths(**kwargs): # keyword arguments
    print(kwargs)
    return sum(kwargs.values())

result = do_maths(x=2, y=3, z=4)

{'x': 2, 'y': 3, 'z': 4}

result

9

For more information, see the documentation.

Python - Installation NumPy