如何修复TypeError：+：'int'和'list'的不支持的操作数类型

Question

Hello i am setting a code for rmse but it happen error

import numpy as np

import matplotlib.pyplot as plt

import random

data=[[235,591],[216,539],[148,413],[35,310],[85,308],[204,519],[49,325],[25,332],[173,498],[191,498],[134,392],[99,334],[117,385],[112,387],[162,425],[272,659],[159,400],[159,427],[59,319],[198,522]]

x_data=[x_row[0] for x_row in data]

y_data=[y_row[1] for y_row in data]

a=np.random.randint(0,10)

b=np.random.randint(0,100)

def f(x):
    return b+a*x

def E(x,y):
    return 0.5*np.sum((y-f(x))**2)

n=1e-3

D=1

count=0

error=E(x_data,y_data)


while D>1e-2:

    tmp0=b-n*np.sum((f(x_data)-y_data))
    tmp1=a-n*np.sum((f(x_data)-y_data)*x_data)
    b=tmp0
    a=tmp1
    current_error=E(x_data,y_data)
    D=error-current_error
    count=count+1
    if count % 100 == 0 :
        print(count,a,b,current_error,D)

error is

Traceback (most recent call last):
    return b+a*x
TypeError: unsupported operand type(s) for +: 'int' and 'list'

Answer 1

The problem is with

def f(x):
    return b+a*x

In this context, a and b are being interpreted as integers while x is being interpreted as a list.

If your intent is to apply the calculation to every element in x , try something like this:

def f(x):    
    out = [] 
    for i in x:
        out.append(b+a*i)
    return out

You will have similar errors when trying to do more calculations later on where you are using lists in calculations. You will have to make similar changes.

For example:

def E(x,y):
    return 0.5*np.sum((y-f(x))**2)

Will have to be changed to something like:

def E(x,y):
    out = [] 
    for xi, yi in zip(y, f(x)):
        out.append(0.5*np.sum((yi-xi**2)))
    return out

To avoid a TypeError: unsupported operand type(s) for -: 'list' and 'list'