Merge pull request #1676 from vnpy/docs

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@ -102,8 +102,129 @@ def run_backtesting(
 
## 参数优化
vnpy提供2种参数优化的解决方案穷举算法、遗传算法
参数优化功能使用的是穷举算法,即多进程对所有参数组合进行回测,并输出最终解集。其操作流程如下:
 
### 穷举算法
穷举算法原理:
- 输入需要优化的参数名、优化区间、优化步进,以及优化目标。
```
def add_parameter(
self, name: str, start: float, end: float = None, step: float = None
):
""""""
if not end and not step:
self.params[name] = [start]
return
if start >= end:
print("参数优化起始点必须小于终止点")
return
if step <= 0:
print("参数优化步进必须大于0")
return
value = start
value_list = []
while value <= end:
value_list.append(value)
value += step
self.params[name] = value_list
def set_target(self, target_name: str):
""""""
self.target_name = target_name
```
&nbsp;
- 形成全局参数组合, 数据结构为[{key: value, key: value}, {key: value, key: value}]。
```
def generate_setting(self):
""""""
keys = self.params.keys()
values = self.params.values()
products = list(product(*values))
settings = []
for p in products:
setting = dict(zip(keys, p))
settings.append(setting)
return settings
```
&nbsp;
- 遍历全局中的每一个参数组合:遍历的过程即运行一次策略回测,并且返回优化目标数值;然后根据目标数值排序,输出优化结果。
```
def run_optimization(self, optimization_setting: OptimizationSetting, output=True):
""""""
# Get optimization setting and target
settings = optimization_setting.generate_setting()
target_name = optimization_setting.target_name
if not settings:
self.output("优化参数组合为空,请检查")
return
if not target_name:
self.output("优化目标未设置,请检查")
return
# Use multiprocessing pool for running backtesting with different setting
pool = multiprocessing.Pool(multiprocessing.cpu_count())
results = []
for setting in settings:
result = (pool.apply_async(optimize, (
target_name,
self.strategy_class,
setting,
self.vt_symbol,
self.interval,
self.start,
self.rate,
self.slippage,
self.size,
self.pricetick,
self.capital,
self.end,
self.mode
)))
results.append(result)
pool.close()
pool.join()
# Sort results and output
result_values = [result.get() for result in results]
result_values.sort(reverse=True, key=lambda result: result[1])
if output:
for value in result_values:
msg = f"参数:{value[0]}, 目标:{value[1]}"
self.output(msg)
return result_values
```
注意可以使用multiprocessing库来创建多进程实现并行优化。例如若用户计算机是2核优化时间为原来1/2若计算机是10核优化时间为原来1/10。
&nbsp;
穷举算法操作:
- 点击“参数优化”按钮,会弹出“优化参数配置”窗口,用于设置优化目标(如最大化夏普比率、最大化收益回撤比)和设置需要优化的参数以及优化区间,如图。
@ -118,6 +239,153 @@ def run_backtesting(
![](https://vnpy-community.oss-cn-shanghai.aliyuncs.com/forum_experience/yazhang/cta_backtester/optimize_result.png)
&nbsp;
### 遗传算法
遗传算法原理:
- 输入需要优化的参数名、优化区间、优化步进,以及优化目标;
- 形成全局参数组合,该组合的数据结构是列表内镶嵌元组,即[[(key, value), (key, value)] , [(key, value), (key,value)]],与穷举算法的全局参数组合的数据结构不同。这样做的目的是有利于参数间进行交叉互换和变异。
```
def generate_setting_ga(self):
""""""
settings_ga = []
settings = self.generate_setting()
for d in settings:
param = [tuple(i) for i in d.items()]
settings_ga.append(param)
return settings_ga
```
&nbsp;
- 形成个体调用random()函数随机从全局参数组合中获取参数。
```
def generate_parameter():
""""""
return random.choice(settings)
```
&nbsp;
- 定义个体变异规则: 即发生变异时,旧的个体完全被新的个体替代。
```
def mutate_individual(individual, indpb):
""""""
size = len(individual)
paramlist = generate_parameter()
for i in range(size):
if random.random() < indpb:
individual[i] = paramlist[i]
return individual,
```
&nbsp;
- 定义评估函数:入参的是个体,即[(key, value), (key, value)]形式的参数组合然后通过dict()转化成setting字典然后运行回测输出目标优化数值如夏普比率、收益回撤比。(注意,修饰器@lru_cache作用是缓存计算结果避免遇到相同的输入重复计算大大降低运行遗传算法的时间)
```
@lru_cache(maxsize=1000000)
def _ga_optimize(parameter_values: tuple):
""""""
setting = dict(parameter_values)
result = optimize(
ga_target_name,
ga_strategy_class,
setting,
ga_vt_symbol,
ga_interval,
ga_start,
ga_rate,
ga_slippage,
ga_size,
ga_pricetick,
ga_capital,
ga_end,
ga_mode
)
return (result[1],)
def ga_optimize(parameter_values: list):
""""""
return _ga_optimize(tuple(parameter_values))
```
&nbsp;
- 运行遗传算法调用deap库的算法引擎来运行遗传算法其具体流程如下。
1先定义优化方向如夏普比率最大化
2然后随机从全局参数组合获取个体并形成族群
3对族群内所有个体进行评估即运行回测并且剔除表现不好个体
4剩下的个体会进行交叉或者变异通过评估和筛选后形成新的族群到此为止是完整的一次种群迭代过程
5多次迭代后种群内差异性减少整体适应性提高最终输出建议结果。该结果为帕累托解集可以是1个或者多个参数组合。
注意:由于用到了@lru_cache, 迭代中后期的速度回提高非常多,因为很多重复的输入都避免了再次的回测,直接在内存中查询并且返回计算结果。
```
from deap import creator, base, tools, algorithms
creator.create("FitnessMax", base.Fitness, weights=(1.0,))
creator.create("Individual", list, fitness=creator.FitnessMax)
......
# Set up genetic algorithem
toolbox = base.Toolbox()
toolbox.register("individual", tools.initIterate, creator.Individual, generate_parameter)
toolbox.register("population", tools.initRepeat, list, toolbox.individual)
toolbox.register("mate", tools.cxTwoPoint)
toolbox.register("mutate", mutate_individual, indpb=1)
toolbox.register("evaluate", ga_optimize)
toolbox.register("select", tools.selNSGA2)
total_size = len(settings)
pop_size = population_size # number of individuals in each generation
lambda_ = pop_size # number of children to produce at each generation
mu = int(pop_size * 0.8) # number of individuals to select for the next generation
cxpb = 0.95 # probability that an offspring is produced by crossover
mutpb = 1 - cxpb # probability that an offspring is produced by mutation
ngen = ngen_size # number of generation
pop = toolbox.population(pop_size)
hof = tools.ParetoFront() # end result of pareto front
stats = tools.Statistics(lambda ind: ind.fitness.values)
np.set_printoptions(suppress=True)
stats.register("mean", np.mean, axis=0)
stats.register("std", np.std, axis=0)
stats.register("min", np.min, axis=0)
stats.register("max", np.max, axis=0)
algorithms.eaMuPlusLambda(
pop,
toolbox,
mu,
lambda_,
cxpb,
mutpb,
ngen,
stats,
halloffame=hof
)
# Return result list
results = []
for parameter_values in hof:
setting = dict(parameter_values)
target_value = ga_optimize(parameter_values)[0]
results.append((setting, target_value, {}))
return results
```