TypeError：当将 integer 与整数列表相乘时，不能将序列乘以非整数类型的“浮点”

Question

My code:

import numpy as np
import sympy as sym

df = [0.99833714, 0.96852   , 0.95101663, 0.92618755]
mat = list(np.arange(1,5)/2)

def task2(df,mat,comp):
    """
    inputs:
    df - list with discount factors
    mat - list with respective maturities
    comp - either a positive integer for compounding frequency per year or 0 for continuous compounding
    returns: numpy array with spot rates (in decimals p.a.) in the same order as inputs
    """
    
    if comp > 0:
        rate = comp*([x for x in df]**(-1/comp*[y for y in mat])-1)
    else:
        rate = -(1/[y for y in mat])*np.log([x for x in df])
    
    rate.asarray()
    
    return rate

This is the error I get when playing task2(), I don't understand why this yields an error and I couldn't find anything related to it on StackOverflow or elsewhere:

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-102-430bc9fc5d7f> in <module>
----> 1 print(task2(df,mat,2))
      2 print(task2(df,mat,0))

<ipython-input-100-5b721054deb4> in task2(df, mat, comp)
     16 
     17     if comp > 0:
---> 18         rate = comp*([x for x in df]**(-1/comp*[y for y in mat])-1)
     19     else:
     20         rate = -(1/[y for y in mat])*np.log([x for x in df])

TypeError: can't multiply sequence by non-int of type 'float'

Can someone tell me, why I get this error, if `comp is surely an integer?

Answer 1

In the below section of the code, -1/comp will result in a float unless comp is 1 or if you are using Python 2.

(-1/comp*[y for y in mat])