List

s = [10, "math", 2022.01.01T09:10:01, [a, 22, 3.5]]
type(s)

Output: list

1. Access a list item by referring to the position.

   s[3]

   Output: [a, 22, 3.5]

   s[-2]

   Output: 2022.01.01T09:10:01

2. Access list items by slicing. Note that the step parameter cannot be specified in Python Parser.

   s[1:4]

   Output: ['math', 2022.01.01T09:10:01, [a, 22, 3.5]]

   s[2:]

   Output: [2022.01.01T09:10:01, [a, 22, 3.5]]

1. Changing list items

   s[1]="english"

   Output: [10, 'english', 2022.01.01T09:10:01, [a, 22, 3.5]]

   // updating a specific item in a nested list through multiple indices is not supported.
   s[3][1] = 21 // unsupported
   // Rewrite as:
   tmp = s[3]
   tmp[1] = 21
   s

   Output: [10, 'english', 2022.01.01T09:10:01, [a, 21, 3.5]]

2. Adding list items

   s.append(2020.01.01)

   Output: [10, 'english', 2022.01.01T09:10:01, [a, 21, 3.5], 2020.01.01]

   s.insert(0, 13:30m)

   Output: [13:30m, 10, 'english', 2022.01.01T09:10:01, [a, 21, 3.5], 2020.01.01]

The del keyword is not supported in Python Parser.

s.pop()  // Remove the specified index. If the index is not specified, remove the last item.

Output: 2020.01.01

s

Output: [13:30m, 10, 'english', 2022.01.01T09:10:01, [a, 21, 3.5]]

s.remove(13:30m) // Remove the specified item.
s

Output: [10, 'english', 2022.01.01T09:10:01, [a, 21, 3.5]]

s.clear()  // Empty the list.

Output: []

dir(s)

Output: ['__add__', '__dir__', '__eq__', '__getitem__', '__iadd__', '__imul__', '__init__', '__iter__', '__len__', '__mul__', '__ne__', '__repr__', '__req__', '__rne__', '__str__', 'append', 'clear', 'copy', 'count', 'extend', 'index', 'insert', 'pop', 'remove', 'reverse', 'sort', 'toddb']

toddb is a unique method in Python Parser, which supports converting lists in Python Parser into vectors (regular vectors or tuples) in DolphinDB.

s = [1, 2, 3]
type(s.toddb())

Output: dolphindb.VECTOR.INT

s = [[1, 2], `A, 3.2]
type(s.toddb())

Output: dolphindb.VECTOR.ANY