修复spread问题

strategy/src/predictor.rs

@@ -326,17 +326,17 @@ impl Predictor {
 
         // 开仓信号处理
         let mut signal = Decimal::ZERO;
-        for fair_price_std in &self.fair_price_std_vec {
+        for (i, fair_price_std) in self.fair_price_std_vec.iter().enumerate() {
             if fair_price_std.is_zero() {
                 return;
             }
 
-            self.spread_vec[index] = fair_price_std - self.mid_price;
+            self.spread_vec[i] = fair_price_std - self.mid_price;
 
-            if self.spread_vec[index] > self.params.min_spread {
+            if self.spread_vec[i] > self.params.min_spread {
                 signal = signal + Decimal::ONE;
             }
-            if self.spread_vec[index] < -self.params.min_spread {
+            if self.spread_vec[i] < -self.params.min_spread {
                 signal = signal - Decimal::ONE;
             }
         }