Source code for cleanlab.dataset

# Copyright (C) 2017-2022  Cleanlab Inc.
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#
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"""
Provides dataset-level and class-level overviews of issues in your dataset. If your task allows you to modify the classes in your dataset, this module can help you determine which classes to remove (see :py:func:rank_classes_by_label_quality <cleanlab.dataset.rank_classes_by_label_quality>) and which classes to merge (see :py:func:find_overlapping_classes <cleanlab.dataset.find_overlapping_classes>).
"""

import numpy as np
import pandas as pd
from cleanlab.count import estimate_joint

[docs]def rank_classes_by_label_quality(
labels=None,
pred_probs=None,
*,
class_names=None,
num_examples=None,
joint=None,
confident_joint=None,
multi_label=False,
) -> pd.DataFrame:
"""
Returns a Pandas DataFrame with all classes and three overall class label quality scores
(details about each score are listed in the Returns parameter). By default, classes are ordered
by "Label Quality Score", ascending, so the most problematic classes are reported first.

Score values are unnormalized and may tend to be very small. What matters is their relative
ranking across the classes.

This method works by providing any one (and only one) of the following inputs:

1. labels and pred_probs, or
2. joint and num_examples, or
3. confident_joint

Only provide **exactly one of the above input options**, do not provide a combination.

**Parameters**: For parameter info, see the docstring of :py:func:find_overlapping_classes <cleanlab.dataset.find_overlapping_classes>.

Returns
-------
overall_label_quality : pd.DataFrame
Pandas DataFrame with cols "Class Index", "Label Issues", "Inverse Label Issues",
"Label Issues", "Inverse Label Noise", "Label Quality Score",
with a description of each of these columns below.
The length of the DataFrame is num_classes (one row per class).
Noise scores are between 0 and 1, where 0 implies no label issues
in the class. The "Label Quality Score" is also between 0 and 1 where 1 implies
perfect quality. Columns:

* *Class Index*: The index of the class in 0, 1, ..., K-1.
* *Label Issues*: count(given_label = k, true_label != k), estimated number of examples in the dataset that are labeled as class k but should have a different label.
* *Inverse Label Issues*: count(given_label != k, true_label = k), estimated number of examples in the dataset that should actually be labeled as class k but have been given another label.
* *Label Noise*: prob(true_label != k | given_label = k), estimated proportion of examples in the dataset that are labeled as class k but should have a different label. For each class k: this is computed by dividing the number of examples with "Label Issues" that were labeled as class k by the total number of examples labeled as class k.
* *Inverse Label Noise*: prob(given_label != k | true_label = k), estimated proportion of examples in the dataset that should actually be labeled as class k but have been given another label.
* *Label Quality Score*: p(true_label = k | given_label = k). This is the proportion of examples with given label k that have been labeled correctly, i.e. 1 - label_noise.

By default, the DataFrame is ordered by "Label Quality Score", ascending.
"""

if joint is None:
joint = estimate_joint(
labels=labels,
pred_probs=pred_probs,
confident_joint=confident_joint,
multi_label=multi_label,
)
if num_examples is None:
num_examples = _get_num_examples(labels=labels)
given_label_noise = joint.sum(axis=1) - joint.diagonal()  # p(s=k) - p(s=k,y=k) = p(y!=k, s=k)
true_label_noise = joint.sum(axis=0) - joint.diagonal()  # p(y=k) - p(s=k,y=k) = p(s!=k,y=k)
given_conditional_noise = given_label_noise / joint.sum(axis=1)  # p(y!=k, s=k) / p(s=k)
true_conditional_noise = true_label_noise / joint.sum(axis=0)  # p(s!=k, y=k) / p(y=k)
df = pd.DataFrame(
{
"Class Index": np.arange(len(joint)),
"Label Issues": (given_label_noise * num_examples).round().astype(int),
"Inverse Label Issues": (true_label_noise * num_examples).round().astype(int),
"Label Noise": given_conditional_noise,  # p(y!=k | s=k)
"Inverse Label Noise": true_conditional_noise,  # p(s!=k | y=k)
# Below could equivalently be computed as: joint.diagonal() / joint.sum(axis=1)
"Label Quality Score": 1 - given_conditional_noise,  # p(y=k | s=k)
}
)
if class_names is not None:
df.insert(loc=0, column="Class Name", value=class_names)
return df.sort_values(by="Label Quality Score", ascending=True).reset_index(drop=True)

[docs]def find_overlapping_classes(
labels=None,
pred_probs=None,
*,
asymmetric=False,
class_names=None,
num_examples=None,
joint=None,
confident_joint=None,
multi_label=False,
) -> pd.DataFrame:
"""Returns the pairs of classes that are often mislabeled as one another.
Consider merging the top pairs of classes returned by this method each into a single class.
If the dataset is labeled by human annotators, consider clearly defining the
difference between the classes prior to having annotators label the data.

This method provides two scores in the Pandas DataFrame that is returned:

* **Num Overlapping Examples**: The number of examples where the two classes overlap
* **Joint Probability**: (num overlapping examples / total number of examples in the dataset).

This method works by providing any one (and only one) of the following inputs:

1. labels and pred_probs, or
2. joint and num_examples, or
3. confident_joint

Only provide **exactly one of the above input options**, do not provide a combination.

This method uses the joint distribution of noisy and true labels to compute ontological
issues via the approach published in Northcutt et al.,
2021 <https://jair.org/index.php/jair/article/view/12125>_.

Note
----
The joint distribution of noisy and true labels is asymmetric, and therefore the joint
probability p(given="vehicle", true="truck") != p(true="truck", given="vehicle").
This is intuitive. Images of trucks (true label) are much more likely to be labeled as a car
(given label) than images of cars (true label) being frequently mislabeled as truck (given
label). cleanlab takes these differences into account for you automatically via the joint
distribution. If you do not want this behavior, simply set asymmetric=False.

This method estimates how often the annotators confuse two classes.
This differs from just using a similarity matrix or confusion matrix,
as these summarize characteristics of the predictive model rather than the data labelers (i.e. annotators).
Instead, this method works even if the model that generated pred_probs tends to be more confident in some classes than others.

Parameters
----------
labels : np.ndarray, optional
An array of shape (N,) of noisy labels, i.e. some labels may be erroneous.
Elements must be in the set 0, 1, ..., K-1, where K is the number of classes.
All the classes (0, 1, ..., and K-1) MUST be present in labels, such that
len(set(labels)) == pred_probs.shape[1] for standard multi-class classification with single-labeled data (e.g. labels =  [1,0,2,1,1,0...]).
For multi-label classification where each example can belong to multiple classes(e.g. labels = [[1,2],[1],[0],..]),
your labels should instead satisfy: len(set(k for l in labels for k in l)) == pred_probs.shape[1]).

pred_probs : np.ndarray, optional
An array of shape (N, K) of model-predicted probabilities,
P(label=k|x). Each row of this matrix corresponds
to an example x and contains the model-predicted probabilities that
x belongs to each possible class, for each of the K classes. The
columns must be ordered such that these probabilities correspond to
class 0, 1, ..., K-1. pred_probs should have been computed using 3 (or
higher) fold cross-validation.

asymmetric : bool, optional
If asymmetric=True, returns separate estimates for both pairs (class1, class2) and (class2, class1). Use this
for finding "is a" relationships where for example "class1 is a class2".
In this case, num overlapping examples counts the number of examples that have been labeled as class1 which should actually have been labeled as class2.
If asymmetric=False, the pair (class1, class2) will only be returned once with an arbitrary order.
In this case, their estimated score is the sum: score(class1, class2) + score(class2, class1)).

class_names : Iterable[str]
A list or other iterable of the string class names. The list should be in the order that
matches the class indices. So if class 0 is 'dog' and class 1 is 'cat', then
class_names = ['dog', 'cat'].

num_examples : int or None, optional
The number of examples in the dataset, i.e. len(labels). You only need to provide this if
you use this function with the joint, e.g. find_overlapping_classes(joint=joint), otherwise
this is automatically computed via sum(confident_joint) or len(labels).

joint : np.ndarray, optional
An array of shape (K, K), where K is the number of classes,
representing the estimated joint distribution of the noisy labels and
true labels. The sum of all entries in this matrix must be 1 (valid
probability distribution). Each entry in the matrix captures the co-occurence joint
probability of a true label and a noisy label, i.e. p(noisy_label=i, true_label=j).
**Important**. If you input the joint, you must also input num_examples.

confident_joint : np.ndarray, optional
An array of shape (K, K) representing the confident joint, the matrix used for identifying label issues, which
estimates a confident subset of the joint distribution of the noisy and true labels, P_{noisy label, true label}.
Entry (j, k) in the matrix is the number of examples confidently counted into the pair of (noisy label=j, true label=k) classes.
The confident_joint can be computed using :py:func:count.compute_confident_joint <cleanlab.count.compute_confident_joint>.
If not provided, it is computed from the given (noisy) labels and pred_probs.

multi_label : bool, optional
If True, labels should be an iterable (e.g. list) of iterables, containing a
list of labels for each example, instead of just a single label.
The multi-label setting supports classification tasks where an example has 1 or more labels.
Example of a multi-labeled labels input: [[0,1], [1], [0,2], [0,1,2], [0], [1], ...].

Returns
-------
overlapping_classes : pd.DataFrame
Pandas DataFrame with columns "Class Index A", "Class Index B",
"Num Overlapping Examples", "Joint Probability" and a description of each below.
Each row corresponds to a pair of classes.

* *Class Index A*: the index of a class in 0, 1, ..., K-1.
* *Class Index B*: the index of a different class (from Class A) in 0, 1, ..., K-1.
* *Num Overlapping Examples*: estimated number of labels overlapping between the two classes.
* *Joint Probability*: the *Num Overlapping Examples* divided by the number of examples in the dataset.

By default, the DataFrame is ordered by "Joint Probability" descending.
"""

def _2d_matrix_to_row_column_value_list(matrix):
"""Create a list<tuple> [(row_index, col_index, value)] representation of matrix.

Parameters
----------
matrix : np.ndarray<float>
Any valid np.ndarray 2-d dimensional matrix.

Returns
-------
list<tuple>
A [(row_index, col_index, value)] representation of matrix.
"""

return [(*i, v) for i, v in np.ndenumerate(matrix)]

if joint is None:
joint = estimate_joint(
labels=labels,
pred_probs=pred_probs,
confident_joint=confident_joint,
multi_label=multi_label,
)
if num_examples is None:
num_examples = _get_num_examples(labels=labels)
if asymmetric:
rcv_list = _2d_matrix_to_row_column_value_list(joint)
# Remove diagonal elements
rcv_list = [tup for tup in rcv_list if tup[0] != tup[1]]
else:  # symmetric
# Sum the upper and lower triangles and remove the lower triangle and the diagonal
sym_joint = np.triu(joint) + np.tril(joint).T
rcv_list = _2d_matrix_to_row_column_value_list(sym_joint)
# Provide values only in (the upper triangle) of the matrix.
rcv_list = [tup for tup in rcv_list if tup[0] < tup[1]]
df = pd.DataFrame(rcv_list, columns=["Class Index A", "Class Index B", "Joint Probability"])
num_overlapping = (df["Joint Probability"] * num_examples).round().astype(int)
df.insert(loc=2, column="Num Overlapping Examples", value=num_overlapping)
if class_names is not None:
df.insert(  # type: ignore
loc=0, column="Class Name A", value=df["Class Index A"].apply(lambda x: class_names[x])
)
df.insert(  # type: ignore
loc=1, column="Class Name B", value=df["Class Index B"].apply(lambda x: class_names[x])
)
return df.sort_values(by="Joint Probability", ascending=False).reset_index(drop=True)

[docs]def overall_label_health_score(
labels=None,
pred_probs=None,
*,
num_examples=None,
joint=None,
confident_joint=None,
multi_label=False,
verbose=True,
) -> float:
"""Returns a single score between 0 and 1 measuring the overall quality of all labels in a dataset.
Intuitively, the score is the average correctness of the given labels across all examples in the
dataset. So a score of 1 suggests your data is perfectly labeled and a score of 0.5 suggests
half of the examples in the dataset may be incorrectly labeled. Thus, a higher
score implies a higher quality dataset.

This method works by providing any one (and only one) of the following inputs:

1. labels and pred_probs, or
2. joint and num_examples, or
3. confident_joint

Only provide **exactly one of the above input options**, do not provide a combination.

**Parameters**: For parameter info, see the docstring of :py:func:find_overlapping_classes <cleanlab.dataset.find_overlapping_classes>.

Returns
-------
health_score : float
A score between 0 and 1, where 1 implies all labels in the dataset are estimated to be correct.
A score of 0.5 implies that half of the dataset's labels are estimated to have issues.
"""

if joint is None:
joint = estimate_joint(
labels=labels,
pred_probs=pred_probs,
confident_joint=confident_joint,
multi_label=multi_label,
)
if num_examples is None:
num_examples = _get_num_examples(labels=labels)
joint_trace = joint.trace()
if verbose:
num_issues = (num_examples * (1 - joint_trace)).round().astype(int)
print(
f" * Overall, about {1 - joint_trace:.0%} ({num_issues:,} of the {num_examples:,}) "
f"labels in your dataset have potential issues.\n"
f" ** The overall label health score for this dataset is: {joint_trace:.2f}."
)
return joint_trace

[docs]def health_summary(
labels=None,
pred_probs=None,
*,
asymmetric=False,
class_names=None,
num_examples=None,
joint=None,
confident_joint=None,
multi_label=False,
verbose=True,
) -> dict:
"""Prints a health summary of your datasets including useful statistics like:

* The classes with the most and least label issues
* Classes that overlap and could potentially be merged
* Overall data label quality health score statistics for your dataset

This method works by providing any one (and only one) of the following inputs:

1. labels and pred_probs, or
2. joint and num_examples, or
3. confident_joint

Only provide **exactly one of the above input options**, do not provide a combination.

**Parameters**: For parameter info, see the docstring of :py:func:find_overlapping_classes <cleanlab.dataset.find_overlapping_classes>.

Returns
-------
summary : dict
A dictionary containing keys (see the corresponding functions' documentation to understand the values):

- "overall_label_health_score", corresponding to :py:func:overall_label_health_score <cleanlab.dataset.overall_label_health_score>
- "joint", corresponding to :py:func:estimate_joint <cleanlab.count.estimate_joint>
- "classes_by_label_quality", corresponding to :py:func:rank_classes_by_label_quality <cleanlab.dataset.rank_classes_by_label_quality>
- "overlapping_classes", corresponding to :py:func:find_overlapping_classes <cleanlab.dataset.find_overlapping_classes>
"""
from cleanlab.internal.util import smart_display_dataframe

if joint is None:
joint = estimate_joint(
labels=labels,
pred_probs=pred_probs,
confident_joint=confident_joint,
multi_label=multi_label,
)
if num_examples is None:
num_examples = _get_num_examples(labels=labels)

if verbose:
longest_line = (
f"|   for your dataset with {num_examples:,} examples "
f"and {len(joint):,} classes.  |\n"
)
print(
"-" * (len(longest_line) - 1)
+ "\n"
+ f"|  Generating a Cleanlab Dataset Health Summary{' ' * (len(longest_line) - 49)}|\n"
+ longest_line
+ f"|  Note, Cleanlab is not a medical doctor... yet.{' ' * (len(longest_line) - 51)}|\n"
+ "-" * (len(longest_line) - 1)
+ "\n",
)

df_class_label_quality = rank_classes_by_label_quality(
labels=labels,
pred_probs=pred_probs,
class_names=class_names,
num_examples=num_examples,
joint=joint,
confident_joint=confident_joint,
multi_label=multi_label,
)
if verbose:
print("Overall Class Quality and Noise across your dataset (below)")
print("-" * 60, "\n", flush=True)
smart_display_dataframe(df_class_label_quality)

df_overlapping_classes = find_overlapping_classes(
labels=labels,
pred_probs=pred_probs,
asymmetric=asymmetric,
class_names=class_names,
num_examples=num_examples,
joint=joint,
confident_joint=confident_joint,
multi_label=multi_label,
)
if verbose:
print(
"\nClass Overlap. In some cases, you may want to merge classes in the top rows (below)"
+ "\n"
+ "-" * 83
+ "\n",
flush=True,
)
smart_display_dataframe(df_overlapping_classes)
print()

health_score = overall_label_health_score(
labels=labels,
pred_probs=pred_probs,
num_examples=num_examples,
joint=joint,
confident_joint=confident_joint,
multi_label=multi_label,
verbose=verbose,
)
if verbose:
print("\nGenerated with <3 from Cleanlab.\n")
return {
"overall_label_health_score": health_score,
"joint": joint,
"classes_by_label_quality": df_class_label_quality,
"overlapping_classes": df_overlapping_classes,
}

def _get_num_examples(labels=None) -> int:
"""Helper method that finds the number of examples from the parameters or throws an error
if neither parameter is provided.

Parameters
----------
For parameter info, see the docstring of dataset.find_overlapping_classes

Returns
-------
num_examples : int
The number of examples in the dataset.

Raises
------
ValueError
If labels is None."""

if labels is not None:
num_examples = len(labels)
else:
raise ValueError(
"Error: num_examples is None. You must provide a value for num_examples "
"when calling this method using the joint as an input parameter."
)
return num_examples