PYTHON

Creating a list with list comprehensions

# construct a basic list using range() and list comprehensions
# syntax
# [ expression for item in list ]
digits = [x for x in range(10)]

print(digits)

List Comprehension generate a list

# generate a list
li = [ i+1 for i in [1,2,3] ]
print(li)
# [2, 3, 4]

Writing a List Comprehension

# Define a generic 1D list of constants
my_list = [2, 5, -4, 6]

# Duplicate a 1D list of constants
[item for item in my_list]

# Duplicate and scale a 1D list of constants
[2 * item for item in my_list]

# Duplicate and filter out non-negatives from 1D list of constants
[item for item in my_list if item < 0]

# Duplicate, filter, and scale a 1D list of constants
[2 * item for item in my_list if item < 0]

# Generate all possible pairs from two lists
[(a, b) for a in (1, 3, 5) for b in (2, 4, 6)]

# Redefine list of contents to be 2D
my_list = [[1, 2], [3, 4]]

# Duplicate a 2D list
[[item for item in sub_list] for sub_list in my_list]

# Duplicate an n-dimensional list
def deep_copy(to_copy): 
  if type(to_copy) is list: 
    return [deep_copy(item) for item in to_copy] 
  else: 
    return to_copy