Linear Algebra program via Python

Source code is below. No copyrights.

import numpy as np
import os

arrs=[]

for file in os.listdir():
if file.endswith(".csv"):
with open(file) as file_name:
arr = np.loadtxt(file_name, delimiter=",")
if len(arr.shape)==1:
print(file)
print(arr)
convert=input("Enter c to convert to column vector.")
if convert=="c":
arr=arr.reshape(arr.shape[0],1)
else:
arr=[arr.tolist()]
arr=np.array(arr)
arrs.append(arr)
print("\n")

def display():
i=0
for x in arrs:
print("Array " + str(i))
print(x)
i=i+1

display()
print("\n")

def add(A,B):
S=[[A[j,i]+B[j,i] for i in range(A.shape[1])]
for j in range(A.shape[0])]
S=np.array(S)
return S

def difference(A,B):
D=[[A[j,i]-B[j,i] for i in range(A.shape[1])]
for j in range(A.shape[0])]
D=np.array(D)
return D

def scalar_product(A,k):
kA=[[A[j,i]*k for i in range(A.shape[1])]
for j in range(A.shape[0])]
kA=np.array(kA)
return kA

def product(A,B):
if A.shape[0]!=B.shape[1]:
return "Column of A does not meet to row of B."
else:
def element(i,j):
c=[A[j,k]*B[k,i] for k in range(A.shape[1])]
return sum(c)
AB=[[element(i,j)
for i in range(A.shape[1])]
for j in range(B.shape[0])]
AB=np.array(AB)
return AB

def save(A):
arrs.append(A)
print("Array "+ str(len(arrs)-1))
print(arrs[-1])

while 0==0:
operator=input("Enter command:")
if operator=="+":
arr1=arrs[int(input("Enter the number of first array."))]
arr2=arrs[int(input("Enter the number of second array."))]
ANS=add(arr1,arr2)
print(str(arr1)+"\n+\n"+str(arr2)+"\n=\n"+str(ANS))
operator=input("Enter S to save the result.")
if operator=="S":
save(ANS)
elif operator=="-":
arr1=arrs[int(input("Enter the number of first array."))]
arr2=arrs[int(input("Enter the number of second array."))]
ANS=difference(arr1,arr2)
print(str(arr1)+"\n-\n"+str(arr2)+"\n=\n"+str(ANS))
operator=input("Enter S to save the result.")
if operator=="S":
save(ANS)
elif operator=="kA":
arr1=arrs[int(input("Enter the number of array."))]
scalar=float(input("Enter the scalar."))
ANS=scalar_product(arr1,scalar)
print(str(arr1)+"\n*\n"+str(scalar)+"\n=\n"+str(ANS))
operator=input("Enter S to save the result.")
if operator=="S":
save(ANS)
elif operator=="*":
arr1=arrs[int(input("Enter the number of first array."))]
arr2=arrs[int(input("Enter the number of second array."))]
ANS=product(arr1,arr2)
print(str(arr1)+"\n*\n"+str(arr2)+"\n=\n"+str(ANS))
operator=input("Enter S to save the result.")
if operator=="S":
save(ANS)
elif operator=="d":
display()
elif operator=="x":
display()
operator=int(input("Enter the number of array to delete."))
arrs.pop(operator)
display()
print("\n")