Lists (Python)

Een list is een geordende groep items of elementen. De elementen in een list kunnen van verschillende types zijn. Lists kunnen cijfers, string en andere lists bevatten.

Voorbeelden

Gebaseerd op [1]:

list1 = []                      # A new empty list
list2 = [1, 2, 3, "cat"]        # A new non-empty list with mixed item types
print(list2[0])                 # Index begint bij 0
print(list2[4])                 # IndexError: list index out of range
list1.append("cat")             # Add a single member, at the end of the list - Ronde haakjes
list1.extend(["dog", "mouse"])  # Add several members - Vierkante + ronde haakjes
list1.insert(0, "fly")          # Insert at the beginning - Rest schuift op
list1[0:0] = ["cow", "doe"]     # Add members at the beginning - Rest schuift op - Blijkbaar zorgt ":0" voor invoegen ipv. vervangen???
list1[0] =  ["cow", "doe"]      # Item 1 is nu vervangen door een twee-dimensionale lijst
doe = list1.pop(1)              # Remove item at index
if "cat" in list1:              # Membership test
  list1.remove("cat")           # Remove AKA delete
#list1.remove("elephant") - throws an error

for item in list1:              # Iterate over items 
  print(item)

print "Item count:", len(list1) # Length AKA size AKA item count
list3 = [6, 7, 8, 9]
for i in range(0, len(list3)):  # Read-write iteration AKA for each item
  list3[i] += 1                 # Item access AKA element access by index
last = list3[-1]                # Last item
nextToLast = list3[-2]          # Next-to-last item
isempty = len(list3) == 0       # Test for emptiness
set1 = set(["cat", "dog"])      # Initialize set from a list
list4 = list(set1)              # Get a list from a set
list5 = list4[:]                # A shallow list copy
list4equal5 = list4==list5      # True: same by value
list4refEqual5 = list4 is list5 # False: not same by reference
list6 = list4[:]
del list6[:]                    # Clear AKA empty AKA erase
list7 = [1, 2] + [2, 3, 4]      # Concatenation
print list1, list2, list3, list4, list5, list6, list7
print list4equal5, list4refEqual5
print list3[1:3], list3[1:], list3[:2] # Slices
print max(list3 ), min(list3 ), sum(list3) # Aggregates

print [x for x in range(10)]    # List comprehension
print [x for x in range(10) if x % 2 == 1]
print [x for x in range(10) if x % 2 == 1 if x < 5]
print [x + 1 for x in range(10) if x % 2 == 1]
print [x + y for x in '123' for y in 'abc']

Bronnen

• https://en.wikibooks.org/wiki/Python_Programming/Lists