Check each number python

Question

I am trying to read a file and check to see that every number is present, all unique. I tried checking the equality of the length of the list and the length of the set. I get this error TypeError: unhashable type: 'list' Do i have to convert the list to something else?

Here is code

def readMatrix(filNam):
    matrixList = []
    numFile = open(filNam, "r")
    lines = numFile.readlines()
    for line in lines:
        line = line.split()
        row = []
        for i in line:
            row.append(int(i))
        matrixList.append(row)
    return matrixList

def eachNumPresent(matrix):
    if len(matrix) == len(set(matrix)):
        return True
    else:
        return False

can you paste your exact stacktrace? Your stacktrace does not necessarily correspond to the code you have shown — karthikr
– karthikr, Commented Oct 22, 2014 at 18:50
Do not write if foo: return True; else: return False; write just return foo. — 9000
– 9000, Commented Oct 22, 2014 at 18:51

Bill Letson · Accepted Answer · 2014-10-22 18:57:02Z

2

A list cannot be an element of a set, so you cannot pass a list of lists to set(). You need to unravel the list of lists to a single list, then pass to set (so integers are your set elements).

unraveled = [x for line in matrix for x in line]
return len(unraveled) == len(set(unraveled))

answered Oct 22, 2014 at 18:57

Bill Letson

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9000 · Accepted Answer · 2014-10-22 18:59:42Z

1

Your matrix is a list of lists. When you write set(matrix), Python tries to create a set of all rows of the matrix. Your rows are lists, which are mutable and unhashable.

What you want is a set of all values in the matrix. You can count it with an explicit loop:

all_values = set()
for row in matrix:
  all_values.update(row)
# here all_values contains all distinct values form matrix

You could also write a nested list comprehension:

all_values = set(x for row in matrix for x in row)

answered Oct 22, 2014 at 18:59

9000

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Comments

Irshad Bhat · Accepted Answer · 2014-10-22 19:04:16Z

0

"set" doesn't work on list of lists but works fine on list of tuples. So use the below code :

matrixList.append(tuple(row))

instead of :

matrixList.append(row)

answered Oct 22, 2014 at 19:04

Irshad Bhat

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4 Comments

solo fisher Over a year ago

thanks! that fixed the problem, but i was wondering how could i check equality of these three things should i convert the last one to look like the first two? [65, 65, 65, 65, 65] [65, 65, 65, 65, 65] (65, 65)

Irshad Bhat Over a year ago

You can't compare a list with a tuple, they are of different type. You have to have them in same type, either list or tuple, for comparison.

solo fisher Over a year ago

I converted them all to tuple but the last one only has two elements so it doesnt compare the three to true. I want it to be true if all the numbers are the same even if the last one has two elements

Irshad Bhat Over a year ago

Use matrixList.append(tuple(set(row))) instead of matrixList.append(row). It should solve your problem.

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