更新图例，处理小于零的异常数据显示

src/utils/breaks_classification.js

@@ -10,10 +10,12 @@ function prettyBreaksClassification(data, n_classes) {
 
     // const min_val = Math.min(...data);
     // const max_val = Math.max(...data);
-    const min_val = data.reduce((min, val) => Math.min(min, val), Infinity);
+    // const min_val = data.reduce((min, val) => Math.min(min, val), Infinity);
+    // 保证最小值不小于0
+    const min_val = Math.max(data.reduce((min, val) => Math.min(min, val), Infinity), 0);
     const max_val = data.reduce((max, val) => Math.max(max, val), -Infinity);
     const data_range = max_val - min_val;
-
+    
     // 计算基础间隔
     const raw_interval = data_range / n_classes;