SyntaxError：打印中的语法无效 function

Question

I'm working on the below script on my MacbookAir and I'm unclear where this syntax error comes from and tried searching on google why it breaks at the = sign in the print function.

I understood there are different functions to print and tried many of them. But am unclear if I'm using the correct Python version (both 2 and 3 are installed).

Can you please help out?

I get an error in line 61 :

print("The interest rate is too high to trade {}".format(total_profit) , end="\n", file=output_file)

Script:

## Initial values from the Python script 
principal=1000
coupon=0.06
frequency=2
r=0.03
transaction_fee = 0.003*principal

## Amendments to the variables as per question 7
probabilitypayingout=0.85
probabolilitynotpayingout=0.15
notpayingoutfullamount=200
maturity=7
market_price=1070
avoidtradingaboveinterestrate=0.02 

#!/usr/bin/env python3.7
import numpy as np

# Open a file to store output
output_file = open("outputfile.txt", "w")

# print variables of this case
print("The variables used for this calculation are: \n - Probability of paying out the full principal {}.".format(probabilitypayingout), "\n - Probability of paying out partial principal {}.".format(probabolilitynotpayingout), "\n - Amount in case of paying out partial principal {}.".format(notpayingoutfullamount), "\n - Market price bond {}.".format(market_price), "\n - Bond maturity in years {}.".format(maturity), "\n - Coupon rate bond {}.".format(coupon), "\n - Principal bond {}.".format(principal), "\n - Frequency coupon bond {}.".format(frequency) , "\n - Risk free rate {}.".format(r) , "\n - Avoid trading aboe interest rate {}.".format(avoidtradingaboveinterestrate), "\n \n"   )

# calculate true value and decide whether to trade     

true_price=0
principalpayout=(probabilitypayingout*principal)+(probabolilitynotpayingout*notpayingoutfullamount)

for t in range(1,maturity*frequency+1):
  if t<(maturity*frequency):
    true_price = true_price + (coupon/frequency)*principal/(1+(r/frequency))**t  # Present value of coupon payments
  else:
    true_price = true_price + (coupon/frequency)*principal/(1+(r/frequency))**t + principalpayout/(1+(r/frequency))**t  # Present value of coupons and principal

print("The price of the bond according to the pricing model is {}, while the current market price is {}.".format(true_price, market_price)) 

if true_price-transaction_fee>market_price:
  profit = true_price-transaction_fee-market_price
  print("The trade is executed and if the pricing model is correct, the profit will be {}".format(profit), "after deduction of trading fees.")  
else:
  print("The trade was not executed, because the expected profit after transaction fees is negative.")  

# Fifth, mimic changes in market conditions by adjusting the interest rate and market price. The indented code below the "for" line is repeated 1,000 times. 
total_profit=0

for n in range(0,1000):
  # Adds some random noise to the interest rate and market price, so each changes slightly (each time code is executed, values will differ because they are random)
  change_r=np.random.normal(0,0.015)  
  change_market_price=np.random.normal(0,40) 
  r_new = r + change_r
  market_price_new = market_price + change_market_price

  # Sixth, execute trading algorithm using new values  
  true_price_new=0


if r_new>avoidtradingaboveinterestrate:


    print("The interest rate is too high to trade {}".format(total_profit) , end="\n", file=output_file)
    output_file.close()

else:
    for t in range(1,maturity*frequency+1):
        if t<(maturity*frequency):
          true_price_new = true_price_new + (coupon/frequency)*principal/(1+(r_new/frequency))**t
        else:
          true_price_new = true_price_new + (coupon/frequency)*principal/(1+(r_new/frequency))**t + principalpayout/(1+(r_new/frequency))**t

    if true_price_new-transaction_fee>market_price_new:
        trading_profit = true_price_new-transaction_fee-market_price_new
        total_profit = total_profit + trading_profit
      print("The trade was executed and is expected to yield a profit of {}. The total profit from trading is {}.".format(trading_profit,total_profit), end="\n", file=output_file    )

print("The total profit from trading is {}".format(total_profit), end="\n", file=output_file)
output_file.close()

Answer 1

print("The interest rate is too high to trade {}".format(total_profit), end="\n", file=output_file)

Is a Python 3 syntax. Run python3 your_file.py instead of python your_file.py .

Answer 2

I think you're not using the correct python version. The default python version on mac os is still python 2.X to use python 3.x you have to call the interpreter with "python3". Try this command:

python3 PythonMIFIAT.py