如何构建一个简单的加密交易模拟器，第1部分

Step 1: Welcome the user. 

Step 2: We will fetch the cryptocurrency prices during March 7th, 2018 since our database starts at that time. 

Step 3: We will ask the user to invest in one currency.

Step 4: Then, we will run the simulator to see how his crypto asset does in the next 9 days. 

Step 5: We will find the best bid price for that currency, compare it with user's initial investment and display if he made a profit or loss.

def welcome():
   print(“Simple Crypto Trading Simulator”)
   print(“Hey Yo, you are back in time. It’s Wednesday, March 7, 2018 7:39 AM”)
   print(“Here are the crypto currencies you can invest.”)
   print(“Fetching prices … ”)

pip install sqlite3

import sqlite3

connection = sqlite3.connect(‘./currency_monitor.db’)
cursor = connection.cursor()
query = “SELECT first_leg, ask FROM prices WHERE     timestamp=’1520408341.52' AND second_leg=’USD’;”    cursor.execute(query)
coinAskPrices = cursor.fetchall()

coins = {}
for coinAskPrice in coinAskPrices:
    if coinAskPrice[0] in coins:
        continue
    coins[coinAskPrice[0]] = {“price”:coinAskPrice[1], “curreny”:coinAskPrice[0]}
    print(“{} — ${} \n”.format(coinAskPrice[0], round(coinAskPrice[1],4)))
    return coins

def inputBuy():
   print(“Select the crypto curreny you want to buy? \n”)
   curreny = raw_input(“”).upper()
   print(“That’s great. How much quantity you want to buy? \n”)
   quantity = float(raw_input(“”))
   return curreny, quantity

price = coins[currency][‘price’]

import sqlite3
import datetime

def runSimulation(boughtPrice, quantity, currency):
  valueThen = boughtPrice * quantity
  bestPrice, timestamp = fetchBestBidPriceFromDB(currency)
  bestValue = bestPrice * quantity
  priceDifference = (bestValue — valueThen)/float(valueThen) * 100

def fetchBestBidPriceFromDB(currency):
   connection = sqlite3.connect(‘./currency_monitor.db’)
   cursor = connection.cursor()
   query = “SELECT max(bid),timestamp from prices WHERE first_leg=’{}’ and second_leg=’USD’ and timestamp> ‘1520408341.52’”.format(currency)
   cursor.execute(query)
   rows = cursor.fetchone()
   return rows[0], rows[1]

print(“The best bid price for {} was ${} at {} \n”.format(currency, bestPrice, time))
if priceDifference>0:
     print(“Your total asset value is ${}, it has increase by {}% \n”.format(round(bestValue, 4), round(priceDifference,2)))
else:
     print(“Your total asset value is ${}, it has decreased by {} \n”.format(round(bestValue, 4), round(priceDifference,2)))

import time
import sys

def dramaticTyping(string):
   for char in string:
     sys.stdout.write(char)
     sys.stdout.flush()
     time.sleep(0.10)