#
#   list comprehension.
#
list_1 = [3,4,2,9,-5]
print(f"list_1: {list_1}")

#	create list_2 with elements that is 2 times each element in list_1

item = 22
print(f"item: {item}")
list_2 = []
for item in list_1:
	list_2.append(2 * item)
print(f"list_2: {list_2}")
print(f"item: {item}")

#   using list comprehension.
#   better: 
#       (1) more concise.
#       (2) local scope of the iteration variable, item.

item = 37
print(f"item: {item}")
list_3 = [2 * item for item in list_1]
print(f"list_3: {list_3}")
print(f"item: {item}")

#   may add a condition for inclusion in the result.
list_4 = [2 * item for item in list_1 if item >= 0]
print(f"list_4: {list_4}")

#   Advanced examples (beyond CSCI 1470)
list_a = ['Bun', 'Jane', 'Joe']
list_b = [{'name': item, 'member': 'Yes'} for item in list_a]
list_c = [{'name': item, 'member': 'Yes', 'pos':i+1} for i, item in enumerate(list_a)]