class_docstr: A stock trading environment for OpenAI gym
class_docstr_tok: ["A","stock","trading","environment","for","OpenAI","gym"]
code: def _buy_stock(self, index, action):
      def _do_buy():
          if (
              self.state[index + 2 * self.stock_dim + 1] != True
          ):  # check if the stock is able to buy
              # if self.state[index + 1] >0:
              # Buy only if the price is > 0 (no missing data in this particular date)
              available_amount = self.state[0] // (
                  self.state[index + 1] * (1 + self.buy_cost_pct[index])
              )  # when buying stocks, we should consider the cost of trading when calculating available_amount, or we may be have cash<0
              # print('available_amount:{}'.format(available_amount))
  
              # update balance
              buy_num_shares = min(available_amount, action)
              buy_amount = (
                  self.state[index + 1]
                  * buy_num_shares
                  * (1 + self.buy_cost_pct[index])
              )
              self.state[0] -= buy_amount
  
              self.state[index + self.stock_dim + 1] += buy_num_shares
  
              self.cost += (
                  self.state[index + 1]
                  * buy_num_shares
                  * self.buy_cost_pct[index]
              )
              self.trades += 1
          else:
              buy_num_shares = 0
  
          return buy_num_shares
  
      # perform buy action based on the sign of the action
      if self.turbulence_threshold is None:
          buy_num_shares = _do_buy()
      else:
          if self.turbulence < self.turbulence_threshold:
              buy_num_shares = _do_buy()
          else:
              buy_num_shares = 0
              pass
  
      return buy_num_shares
  
imports: from __future__ import annotations
  from typing import List
  import gymnasium
  import matplotlib
  import matplotlib.pyplot
  import numpy
  import pandas
  from gymnasium import spaces
  from gymnasium.utils import seeding
  from stable_baselines3.common.vec_env import DummyVecEnv
label_desc: Use image node_id 3 for calling the StockTradingEnv obj's underlying member method code with example usage: obj._buy_stock(index, action) and returns: buy_num_shares, buy_num_shares