import numpy as np
import pandas as pd
from typing import Union, Iterable

class DataLoader():
    """
    数据类: 数据加载模块
    """
    def __init__(self, path: Union[str, pd.DataFrame]=None):
        if type(path) == str:
            self.data = pd.read_csv(path).set_index(['stock_code']).sort_index()
        if type(path) == pd.DataFrame:
            self.data = path.copy()
        
    def get(self, 
            target: Iterable[str]=[], 
            column: str=''):
        """
        - target: 查询目标代码
        - column(str): 查询列
        """
        res = pd.Series(index=target)
        column_type = self.data[column].dtype
        stock_list = list(set(self.data.index.values) & set(target))
        res.loc[stock_list] = self.data.loc[stock_list, column].values
        stock_list = list(set(target) - set(stock_list))
        if column_type == str:
            res.loc[stock_list] = None
        else:
            res.loc[stock_list] = np.nan
        return res.sort_index()