Java 類名：com.alibaba.alink.operator.batch.evaluation.EvalMultiClassBatchOp

Python 類名：EvalMultiClassBatchOp

功能介紹

多分類評估是對多分類演算法的預測結果進行效果評估。

支援Roc曲線，LiftChart曲線，K-S曲線，Recall-Precision曲線繪製。

流式的實驗支援累計統計和視窗統計，除卻上述四條曲線外，還給出Auc/Kappa/Accuracy/Logloss隨時間的變化曲線。

給出整體的評估指標包括：AUC、K-S、PRC, 不同閾值下的Precision、Recall、F-Measure、Sensitivity、Accuracy、Specificity和Kappa。

混淆矩陣

Precision

Precision = \dfrac{TP}{TP + FP}

Recall

Recall = \dfrac{TP}{TP + FN}

F-Measure

F1=\dfrac{2TP}{2TP+FP+FN}=\dfrac{2\cdot Precision \cdot Recall}{Precision+Recall}

Sensitivity

Sensitivity=\dfrac{TP}{TP+FN}

Accuracy

Accuray=\dfrac{TP + TN}{TP + TN + FP + FN}

Specificity

Specificity=\dfrac{TN}{FP+T}

Kappa

p_a =\dfrac{TP + TN}{TP + TN + FP + FN}

p_e = \dfrac{(TN + FP) * (TN + FN) + (FN + TP) * (FP + TP)}{(TP + TN + FP + FN) * (TP + TN + FP + FN)}

kappa = \dfrac{p_a - p_e}{1 - p_e}

Logloss

logloss=- \dfrac{1}{N}\sum_{i=1}^N \sum_{j=1}^My_{i,j}log(p_{i,j})

引數說明

程式碼示例

Python 程式碼

from pyalink.alink import *
import pandas as pd
useLocalEnv(1)
df = pd.DataFrame([
    ["prefix1", "{\"prefix1\": 0.9, \"prefix0\": 0.1}"],
    ["prefix1", "{\"prefix1\": 0.8, \"prefix0\": 0.2}"],
    ["prefix1", "{\"prefix1\": 0.7, \"prefix0\": 0.3}"],
    ["prefix0", "{\"prefix1\": 0.75, \"prefix0\": 0.25}"],
    ["prefix0", "{\"prefix1\": 0.6, \"prefix0\": 0.4}"]])
inOp = BatchOperator.fromDataframe(df, schemaStr='label string, detailInput string')
metrics = EvalMultiClassBatchOp().setLabelCol("label").setPredictionDetailCol("detailInput").linkFrom(inOp).collectMetrics()
print("Prefix0 accuracy:", metrics.getAccuracy("prefix0"))
print("Prefix1 recall:", metrics.getRecall("prefix1"))
print("Macro Precision:", metrics.getMacroPrecision())
print("Micro Recall:", metrics.getMicroRecall())
print("Weighted Sensitivity:", metrics.getWeightedSensitivity())

Java 程式碼

import org.apache.flink.types.Row;
import com.alibaba.alink.operator.batch.BatchOperator;
import com.alibaba.alink.operator.batch.evaluation.EvalMultiClassBatchOp;
import com.alibaba.alink.operator.batch.source.MemSourceBatchOp;
import com.alibaba.alink.operator.common.evaluation.MultiClassMetrics;
import org.junit.Test;
import java.util.Arrays;
import java.util.List;
public class EvalMultiClassBatchOpTest {
  @Test
  public void testEvalMultiClassBatchOp() throws Exception {
    List <Row> df = Arrays.asList(
      Row.of("prefix1", "{\"prefix1\": 0.9, \"prefix0\": 0.1}"),
      Row.of("prefix1", "{\"prefix1\": 0.8, \"prefix0\": 0.2}"),
      Row.of("prefix1", "{\"prefix1\": 0.7, \"prefix0\": 0.3}"),
      Row.of("prefix0", "{\"prefix1\": 0.75, \"prefix0\": 0.25}")
    );
    BatchOperator <?> inOp = new MemSourceBatchOp(df, "label string, detailInput string");
    MultiClassMetrics metrics = new EvalMultiClassBatchOp().setLabelCol("label").setPredictionDetailCol(
      "detailInput").linkFrom(inOp).collectMetrics();
    System.out.println("Prefix0 accuracy:" + metrics.getAccuracy("prefix0"));
    System.out.println("Prefix1 recall:" + metrics.getRecall("prefix1"));
    System.out.println("Macro Precision:" + metrics.getMacroPrecision());
    System.out.println("Micro Recall:" + metrics.getMicroRecall());
    System.out.println("Weighted Sensitivity:" + metrics.getWeightedSensitivity());
  }
}

執行結果

Prefix0 accuracy: 0.6
Prefix1 recall: 1.0
Macro Precision: 0.8
Micro Recall: 0.6
Weighted Sensitivity: 0.6