in src/datasets/splits.py [0:0]
def subsplit(self, arg=None, k=None, percent=None, weighted=None): # pylint: disable=redefined-outer-name
"""Divides this split into subsplits.
There are 3 ways to define subsplits, which correspond to the 3
arguments `k` (get `k` even subsplits), `percent` (get a slice of the
dataset with `datasets.percent`), and `weighted` (get subsplits with proportions
specified by `weighted`).
Example::
```
# 50% train, 50% test
train, test = split.subsplit(k=2)
# 50% train, 25% test, 25% validation
train, test, validation = split.subsplit(weighted=[2, 1, 1])
# Extract last 20%
subsplit = split.subsplit(datasets.percent[-20:])
```
Warning: k and weighted will be converted into percent which mean that
values below the percent will be rounded up or down. The final split may be
bigger to deal with remainders. For instance:
```
train, test, valid = split.subsplit(k=3) # 33%, 33%, 34%
s1, s2, s3, s4 = split.subsplit(weighted=[2, 2, 1, 1]) # 33%, 33%, 16%, 18%
```
Args:
arg: If no kwargs are given, `arg` will be interpreted as one of
`k`, `percent`, or `weighted` depending on the type.
For example:
```
split.subsplit(10) # Equivalent to split.subsplit(k=10)
split.subsplit(datasets.percent[:-20]) # percent=datasets.percent[:-20]
split.subsplit([1, 1, 2]) # weighted=[1, 1, 2]
```
k: `int` If set, subdivide the split into `k` equal parts.
percent: `datasets.percent slice`, return a single subsplit corresponding to
a slice of the original split. For example:
`split.subsplit(datasets.percent[-20:]) # Last 20% of the dataset`.
weighted: `list[int]`, return a list of subsplits whose proportions match
the normalized sum of the list. For example:
`split.subsplit(weighted=[1, 1, 2]) # 25%, 25%, 50%`.
Returns:
A subsplit or list of subsplits extracted from this split object.
"""
# Note that the percent kwargs redefine the outer name datasets.percent. This
# is done for consistency (.subsplit(percent=datasets.percent[:40]))
if sum(bool(x) for x in (arg, k, percent, weighted)) != 1:
raise ValueError("Only one argument of subsplit should be set.")
# Auto deduce k
if isinstance(arg, int):
k = arg
elif isinstance(arg, slice):
percent = arg
elif isinstance(arg, list):
weighted = arg
if not (k or percent or weighted):
raise ValueError(
f"Invalid split argument {arg}. Only list, slice and int supported. "
"One of k, weighted or percent should be set to a non empty value."
)
def assert_slices_coverage(slices):
# Ensure that the expended slices cover all percents.
assert sum((list(range(*s.indices(100))) for s in slices), []) == list(range(100))
if k:
if not 0 < k <= 100:
raise ValueError(f"Subsplit k should be between 0 and 100, got {k}")
shift = 100 // k
slices = [slice(i * shift, (i + 1) * shift) for i in range(k)]
# Round up last element to ensure all elements are taken
slices[-1] = slice(slices[-1].start, 100)
# Internal check to ensure full coverage
assert_slices_coverage(slices)
return tuple(_SubSplit(self, s) for s in slices)
elif percent:
return _SubSplit(self, percent)
elif weighted:
# Normalize the weighted sum
total = sum(weighted)
weighted = [100 * x // total for x in weighted]
# Create the slice for each of the elements
start = 0
stop = 0
slices = []
for v in weighted:
stop += v
slices.append(slice(start, stop))
start = stop
# Round up last element to ensure all elements are taken
slices[-1] = slice(slices[-1].start, 100)
# Internal check to ensure full coverage
assert_slices_coverage(slices)
return tuple(_SubSplit(self, s) for s in slices)
else:
# Should not be possible
raise ValueError("Could not determine the split")