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F-score

As explained in Machine Learning Algorithms in Depth

The F1 score is the harmonic mean of precision and recall.

The F1 score summarizes classification performance at a fixed threshold as the harmonic mean of precision and recall: F1 = 2PR/(P + R), where P = TP/(TP + FP) and R = TP/(TP + FN). section 5.2

Figure 5.4 Receiver operating characteristic (ROC) plot (left) and precision-recall plot (right)
figure

A precision-recall plot shows the tradeoff as the classification threshold varies; the F1 score summarizes one selected threshold. section 5.2

How Machine Learning Algorithms in Depth covers it

How deep it goes
Defines precision and recall, then gives the harmonic-mean formula without further derivation or implementation.
Examples
Uses precision-recall plots and threshold-specific performance summaries as the concrete evaluation setting.
What you can do after
Evaluate classification performance by combining precision and recall into one threshold-specific statistic.
How it connects
Connects precision, recall, classification thresholds, precision-recall curves, and confusion-matrix counts.

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This explainer was generated by Manning's knowledge graph from the text of Machine Learning Algorithms in Depth. The section links point to the parts of the book it draws on.