[New-bugs-announce] [issue39118] Variables changing values on their own

[Leonardo]

New submission from Leonardo <leonardo.simunovic at gmail.com>:

in this code the variable o changes on its own:

x=[[-1, 7, 3], [12, 2, -13], [14, 18, -8], [17, 4, -4]]
x1=[[-8, -10, 0], [5, 5, 10], [2, -7, 3], [9, -8, -3]]
y=[[0,0,0],[0,0,0],[0,0,0],[0,0,0]]
k=True
f=0
z=[]
d=[]
while k:
    print(k)
    o=x
    print(o)
    for i in range(len(x)):
        for n in range(len(x)):
            if i!=n:
                for g in range(3):
                    if x[i][g]>x[n][g]:
                        y[i][g]-=1
                    if x[i][g]<x[n][g]:
                        y[i][g]+=1
    for i in range(len(x)):
        for n in range(3):
            x[i][n]+=y[i][n]
    for i in range(len(z)):
        if z[i]==x and d[i]==y:
            print("")   
    print(o)
    k=False


A similar error happens when I try to append x values to a list, the list is filled with the same x value (the last one that has been appended) the number of times a x value had been appended in general.

For example:

if I had a values of x at the end of the while loop as 1, 2 and 3 and I appended them to a list the list would be [3, 3, 3] instead of [1, 2, 3]. If i wrote the list out each time a new x value is appended it would write it [1] first, then [2, 2] and then [3, 3, 3] at the end. 

I am really sorry for wasting time if this is just me being really dumb and messing something up.

----------
assignee: terry.reedy
components: IDLE
messages: 358790
nosy: leonardo.simunovic at gmail.com, terry.reedy
priority: normal
severity: normal
status: open
title: Variables changing values on their own
type: behavior
versions: Python 3.7

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Python tracker <report at bugs.python.org>
<https://bugs.python.org/issue39118>
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