Stellen Sie mit Numpy einheitliche Gruppengrößen sicher ⇐ Python

[Anonymous]

Ich habe eine Funktion, die einheitliche Größen für gruppierte Daten gewährleistet, indem fehlende Werte mit einem fill_value gepolstert werden. Die Funktion verwendet derzeit eine für Schleife, um das gepolsterte Array zu füllen.

Code: Select all

def ensure_uniform_groups(
groups: np.ndarray,
values: np.ndarray,
fill_value: np.number = np.nan) -> tuple[np.ndarray, np.ndarray]:
"""
Ensure uniform group lengths by padding each group to the same size.

Args:
groups : np.ndarray
1D array of group identifiers, assumed to be consecutive.
values : np.ndarray
1D/2D array of values corresponding to the group identifiers.
fill_value : np.number, optional
Value to use for padding groups. Default is np.nan.

Returns:
tuple[np.ndarray, np.ndarray]
A tuple containing uniform groups with padded values.
"""
# set common type
dtype = np.result_type(fill_value, values)

# derive group infos
n = groups.size
mask = np.r_[True, groups[:-1] != groups[1:]]
starts = np.arange(n)[mask]
ends = np.r_[starts[1:] - 1, n-1]
sizes = ends - starts + 1
max_size = np.max(sizes)

# check if data is uniform already
if np.all(sizes == max_size):
return groups, values

# generate uniform arrays
unique_groups = groups[starts]
full_groups = np.repeat(unique_groups, max_size)
full_values = np.full((full_groups.shape[0], values.shape[1]), fill_value=fill_value, dtype=dtype)
for i, (ia, ie) in enumerate(np.column_stack([starts, ends+1])):
ua = i * max_size
ue = ua + ie-ia
full_values[ua:ue] = values[ia:ie]
return full_groups, full_values
< /code>
Hier ist ein Beispiel: < /p>
groups = np.array([1, 1, 1, 2, 2, 3])   # size by group should be 3
values = np.column_stack([groups*10, groups*100])
fill_value = np.nan
ugroups, uvalues = ensure_uniform_groups(groups, values, fill_value)
out = np.vstack([ugroups, uvalues.T])
print(out)
# [[  1.   1.   1.   2.   2.   2.   3.   3.   3.]
#  [ 10.  10.  10.  20.  20.  nan  30.  nan  nan]
#  [100. 100. 100. 200. 200.  nan 300.  nan  nan]]