F1 Score¶
Module Interface¶
- class torchmetrics.F1Score(num_classes=None, threshold=0.5, average='micro', mdmc_average=None, ignore_index=None, top_k=None, multiclass=None, compute_on_step=None, **kwargs)[source]
Computes F1 metric.
F1 metrics correspond to a harmonic mean of the precision and recall scores. Works with binary, multiclass, and multilabel data. Accepts logits or probabilities from a model output or integer class values in prediction. Works with multi-dimensional preds and target.
Forward accepts
preds
(float or long tensor):(N, ...)
or(N, C, ...)
where C is the number of classestarget
(long tensor):(N, ...)
If preds and target are the same shape and preds is a float tensor, we use the
self.threshold
argument. This is the case for binary and multi-label logits.If preds has an extra dimension as in the case of multi-class scores we perform an argmax on
dim=1
.- Parameters
num_classes¶ (
Optional
[int
]) – Number of classes. Necessary for'macro'
,'weighted'
andNone
average methods.threshold¶ (
float
) – Threshold for transforming probability or logit predictions to binary(0,1)
predictions, in the case of binary or multi-label inputs. Default value of0.5
corresponds to input being probabilities.Defines the reduction that is applied. Should be one of the following:
'micro'
[default]: Calculate the metric globally, across all samples and classes.'macro'
: Calculate the metric for each class separately, and average the metrics across classes (with equal weights for each class).'weighted'
: Calculate the metric for each class separately, and average the metrics across classes, weighting each class by its support (tp + fn
).'none'
orNone
: Calculate the metric for each class separately, and return the metric for every class.'samples'
: Calculate the metric for each sample, and average the metrics across samples (with equal weights for each sample).
Note
What is considered a sample in the multi-dimensional multi-class case depends on the value of
mdmc_average
.mdmc_average¶ (
Optional
[str
]) –Defines how averaging is done for multi-dimensional multi-class inputs (on top of the
average
parameter). Should be one of the following:None
[default]: Should be left unchanged if your data is not multi-dimensional multi-class.'samplewise'
: In this case, the statistics are computed separately for each sample on theN
axis, and then averaged over samples. The computation for each sample is done by treating the flattened extra axes...
(see Input types) as theN
dimension within the sample, and computing the metric for the sample based on that.'global'
: In this case theN
and...
dimensions of the inputs (see Input types) are flattened into a newN_X
sample axis, i.e. the inputs are treated as if they were(N_X, C)
. From here on theaverage
parameter applies as usual.
ignore_index¶ (
Optional
[int
]) – Integer specifying a target class to ignore. If given, this class index does not contribute to the returned score, regardless of reduction method. If an index is ignored, andaverage=None
or'none'
, the score for the ignored class will be returned asnan
.top_k¶ (
Optional
[int
]) – Number of the highest probability or logit score predictions considered finding the correct label, relevant only for (multi-dimensional) multi-class inputs. The default value (None
) will be interpreted as 1 for these inputs. Should be left at default (None
) for all other types of inputs.multiclass¶ (
Optional
[bool
]) – Used only in certain special cases, where you want to treat inputs as a different type than what they appear to be. See the parameter’s documentation section for a more detailed explanation and examples.compute_on_step¶ (
Optional
[bool
]) –Forward only calls
update()
and returns None if this is set to False.Deprecated since version v0.8: Argument has no use anymore and will be removed v0.9.
kwargs¶ (
Dict
[str
,Any
]) – Additional keyword arguments, see Advanced metric settings for more info.
Example
>>> import torch >>> from torchmetrics import F1Score >>> target = torch.tensor([0, 1, 2, 0, 1, 2]) >>> preds = torch.tensor([0, 2, 1, 0, 0, 1]) >>> f1 = F1Score(num_classes=3) >>> f1(preds, target) tensor(0.3333)
Initializes internal Module state, shared by both nn.Module and ScriptModule.
Functional Interface¶
- torchmetrics.functional.f1_score(preds, target, beta=1.0, average='micro', mdmc_average=None, ignore_index=None, num_classes=None, threshold=0.5, top_k=None, multiclass=None)[source]
Computes F1 metric. F1 metrics correspond to a equally weighted average of the precision and recall scores.
Works with binary, multiclass, and multilabel data. Accepts probabilities or logits from a model output or integer class values in prediction. Works with multi-dimensional preds and target.
If preds and target are the same shape and preds is a float tensor, we use the
self.threshold
argument to convert into integer labels. This is the case for binary and multi-label probabilities or logits.If preds has an extra dimension as in the case of multi-class scores we perform an argmax on
dim=1
.The reduction method (how the precision scores are aggregated) is controlled by the
average
parameter, and additionally by themdmc_average
parameter in the multi-dimensional multi-class case. Accepts all inputs listed in Input types.- Parameters
preds¶ (
Tensor
) – Predictions from model (probabilities, logits or labels)Defines the reduction that is applied. Should be one of the following:
'micro'
[default]: Calculate the metric globally, across all samples and classes.'macro'
: Calculate the metric for each class separately, and average the metrics across classes (with equal weights for each class).'weighted'
: Calculate the metric for each class separately, and average the metrics across classes, weighting each class by its support (tp + fn
).'none'
orNone
: Calculate the metric for each class separately, and return the metric for every class.'samples'
: Calculate the metric for each sample, and average the metrics across samples (with equal weights for each sample).
Note
What is considered a sample in the multi-dimensional multi-class case depends on the value of
mdmc_average
.Note
If
'none'
and a given class doesn’t occur in thepreds
ortarget
, the value for the class will benan
.mdmc_average¶ (
Optional
[str
]) –Defines how averaging is done for multi-dimensional multi-class inputs (on top of the
average
parameter). Should be one of the following:None
[default]: Should be left unchanged if your data is not multi-dimensional multi-class.'samplewise'
: In this case, the statistics are computed separately for each sample on theN
axis, and then averaged over samples. The computation for each sample is done by treating the flattened extra axes...
(see Input types) as theN
dimension within the sample, and computing the metric for the sample based on that.'global'
: In this case theN
and...
dimensions of the inputs (see Input types) are flattened into a newN_X
sample axis, i.e. the inputs are treated as if they were(N_X, C)
. From here on theaverage
parameter applies as usual.
ignore_index¶ (
Optional
[int
]) – Integer specifying a target class to ignore. If given, this class index does not contribute to the returned score, regardless of reduction method. If an index is ignored, andaverage=None
or'none'
, the score for the ignored class will be returned asnan
.num_classes¶ (
Optional
[int
]) – Number of classes. Necessary for'macro'
,'weighted'
andNone
average methods.threshold¶ (
float
) – Threshold for transforming probability or logit predictions to binary (0,1) predictions, in the case of binary or multi-label inputs. Default value of 0.5 corresponds to input being probabilities.Number of highest probability or logit score predictions considered to find the correct label, relevant only for (multi-dimensional) multi-class inputs. The default value (
None
) will be interpreted as 1 for these inputs.Should be left at default (
None
) for all other types of inputs.multiclass¶ (
Optional
[bool
]) – Used only in certain special cases, where you want to treat inputs as a different type than what they appear to be. See the parameter’s documentation section for a more detailed explanation and examples.
- Return type
- Returns
The shape of the returned tensor depends on the
average
parameterIf
average in ['micro', 'macro', 'weighted', 'samples']
, a one-element tensor will be returnedIf
average in ['none', None]
, the shape will be(C,)
, whereC
stands for the number of classes
Example
>>> from torchmetrics.functional import f1_score >>> target = torch.tensor([0, 1, 2, 0, 1, 2]) >>> preds = torch.tensor([0, 2, 1, 0, 0, 1]) >>> f1_score(preds, target, num_classes=3) tensor(0.3333)