接着上面的回答,请告诉鲸鱼优化算法WOA原始代码优化XGBoost模型,优化模型寻找最优参数的过程
时间: 2023-06-24 16:07:03 浏览: 106
好的,以下是鲸鱼优化算法WOA原始代码优化XGBoost模型的过程:
1.导入必要的库和模块
```python
import numpy as np
import xgboost as xgb
from sklearn.datasets import load_breast_cancer
from sklearn.model_selection import train_test_split
from sklearn.metrics import accuracy_score
```
2.加载数据集并进行训练集和测试集的划分
```python
data = load_breast_cancer()
X_train, X_test, y_train, y_test = train_test_split(data.data, data.target, test_size=0.3, random_state=42)
```
3.定义XGBoost模型
```python
def xgb_model(params):
model = xgb.XGBClassifier(n_estimators=100,
learning_rate=params[0],
max_depth=int(params[1]),
subsample=params[2],
gamma=params[3],
reg_lambda=params[4],
colsample_bytree=params[5],
objective='binary:logistic')
model.fit(X_train, y_train)
y_pred = model.predict(X_test)
accuracy = accuracy_score(y_test, y_pred)
return accuracy
```
4.定义WOA算法
```python
def WOA(obj_func, lb, ub, dim, search_agents=30, max_iter=100):
# 初始化搜索代理的位置和速度
positions = np.zeros((search_agents, dim))
for i in range(dim):
positions[:, i] = np.random.uniform(0, 1, size=search_agents) * (ub - lb) + lb
for i in range(search_agents):
fitness = obj_func(positions[i, :])
if i == 0:
best_fitness = fitness
best_position = positions[i, :]
elif fitness > best_fitness:
best_fitness = fitness
best_position = positions[i, :]
# 开始迭代
for t in range(max_iter):
a = 2 - 2 * t / max_iter # 调整参数a,使得搜索代理的行为更加随机
for i in range(search_agents):
r1 = np.random.uniform(size=dim)
r2 = np.random.uniform(size=dim)
A = 2 * a * r1 - a
C = 2 * r2
b = 1
if np.random.uniform() < 0.5:
D = np.abs(C * best_position - positions[i, :])
new_position = best_position - A * D
else:
rand_leader_index = np.random.randint(0, search_agents)
X_rand = positions[rand_leader_index, :]
D = np.abs(C * X_rand - positions[i, :])
new_position = X_rand - A * D
# 边界处理
new_position = np.clip(new_position, lb, ub)
new_fitness = obj_func(new_position)
# 更新最优位置
if new_fitness > best_fitness:
best_fitness = new_fitness
best_position = new_position
# 更新当前位置
positions[i, :] = new_position
return best_position, best_fitness
```
5.定义搜索空间和运行WOA算法
```python
search_space = [(0.01, 1), # learning_rate
(1, 10), # max_depth
(0.1, 1), # subsample
(0, 1), # gamma
(0, 10), # reg_lambda
(0.1, 1)] # colsample_bytree
dim = len(search_space)
lb = [item[0] for item in search_space]
ub = [item[1] for item in search_space]
best_position, best_fitness = WOA(xgb_model, lb, ub, dim, search_agents=30, max_iter=100)
print('Best accuracy:', best_fitness)
print('Best parameters:', best_position)
```
经过WOA算法的优化寻找,可以得到最优的XGBoost模型参数,从而达到优化模型的目的。
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