ak.contents.ListOffsetArray

Defined in awkward.contents.listoffsetarray on line 56.

class ak.contents.ListOffsetArray(offsets, content, *, parameters=None)

ListOffsetArray describes unequal-length lists (often called a “jagged” or “ragged” array). Like ak.contents.RegularArray, the underlying data for all lists are in a contiguous content. It is subdivided into lists according to an offsets buffer, which specifies the starting and stopping index of each list.

The offsets must have at least length 1 (corresponding to an empty array), but it need not start with 0 or include all of the content. Just as ak.contents.RegularArray can have unreachable content if it is not an integer multiple of size, a ListOffsetArray can have unreachable content before the start of the first list and after the end of the last list.

Like ak.contents.RegularArray and ak.contents.ListArray, a ListOffsetArray can represent strings if its __array__ parameter is "string" (UTF-8 assumed) or "bytestring" (no encoding assumed) and it contains an ak.contents.NumpyArray of dtype=np.uint8 whose __array__ parameter is "char" (UTF-8 assumed) or "byte" (no encoding assumed).

ListOffsetArray corresponds to Apache Arrow List type.

To illustrate how the constructor arguments are interpreted, the following is a simplified implementation of __init__, __len__, and __getitem__:

class ListOffsetArray(Content):

def __init__(self, offsets, content):

assert isinstance(offsets, (Index32, IndexU32, Index64)) assert isinstance(content, Content) assert len(offsets) != 0 for i in range(len(offsets) - 1):

start = offsets[i] stop = offsets[i + 1] if start != stop:

assert start < stop # i.e. start <= stop assert start >= 0 assert stop <= len(content)

self.offsets = offsets self.content = content

def __len__(self):

return len(self.offsets) - 1

def __getitem__(self, where):

if isinstance(where, int):

if where < 0:

where += len(self)

assert 0 <= where < len(self) return self.content[self.offsets[where] : self.offsets[where + 1]]

elif isinstance(where, slice) and where.step is None:

offsets = self.offsets[where.start : where.stop + 1] if len(offsets) == 0:

offsets = [0]

return ListOffsetArray(offsets, self.content)

elif isinstance(where, str):

return ListOffsetArray(self.offsets, self.content[where])

else:

raise AssertionError(where)

property offsets: awkward.index.Index

form_cls: awkward._typing.Final

copy(offsets=UNSET, content=UNSET, *, parameters=UNSET)

classmethod simplified(offsets, content, *, parameters=None)

property starts: awkward.index.Index

property stops

property length: awkward._nplikes.shape.ShapeItem

to_ListOffsetArray64(start_at_zero: bool = False) → ListOffsetArray

to_RegularArray()