I am getting a error: "int object is not callable" on line 19

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What should I do to fix this error?
"int object is not callable"

<pre>def isTriangular(x):
    """Returns whether or not a given number x is triangular.
    
    The triangular number Tn is a number that can be represented in the form of a triangular 
    grid of points where the first row contains a single element and each subsequent row contains 
    one more element than the previous one.
    
    We can just use the fact that the nth triangular number can be found by using a formula: Tn = n(n + 1) / 2.
    
    Example: 3 is triangular since 3 = 2(3) / 2
    3 --> 2nd position: (2 * 3 / 2)
    
    Example: 15 is triangular since 15 = 5(6) / 2
    15 --> 5th position: (5 * 6 / 2)
    """
    
    # your code here
    i = 0
    for i in range(1 + i, x + 1):
        triangle = i(i + 1) / 2
        if triangle == x:
            return True
        elif i >= triangle:
            return False
        
isTriangular(3)

What I have tried:

I have tried to concatenate the integer but it's not possible. It should have substituted the values of i and applied it to the expression but I don't have any clue what the error means...

Posted 28-Aug-21 20:38pm

Mr. Expert 2021

Updated 29-Aug-21 2:04am

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Richard MacCutchan · Accepted Answer · 2021-08-29T02:04:00

Solution 3

The problem is that you break out of the loop as soon as you find a value that is not triangular. So for the input value 3 you break out when the loop count reaches 2. You need to continue the loop until you find a match, or the loop terminates. So set a flag at the beginning which you can use after the loop terminates to check if you found the number. something like:

Python

def isTriangular(x):
    found = False # assume no find
    for i in range(1, x + 1):
        triangle = i * (i + 1) / 2
        if triangle == x:
            found = True
            break # terminate if the number is found

    return found

Posted 29-Aug-21 2:04am

Richard MacCutchan

Comments

Mr. Expert 2021 29-Aug-21 8:09am

Got it thanks man

Mr. Expert 2021 29-Aug-21 8:10am

When I enter a non-triangular number. It doesn't print anything.

def isTriangular(x):
"""Returns whether or not a given number x is triangular.

The triangular number Tn is a number that can be represented in the form of a triangular
grid of points where the first row contains a single element and each subsequent row contains
one more element than the previous one.

We can just use the fact that the nth triangular number can be found by using a formula: Tn = n(n + 1) / 2.

Example: 3 is triangular since 3 = 2(3) / 2
3 --> 2nd position: (2 * 3 / 2)

Example: 15 is triangular since 15 = 5(6) / 2
15 --> 5th position: (5 * 6 / 2)
"""

# your code here
i = 0
for i in range(1 + i, x + 1):
triangle = i * (i + 1) / 2
if triangle == x:
print("True")
elif i > triangle:
print("False")

isTriangular(24)

Richard MacCutchan 29-Aug-21 8:16am

Yes because you have changed from the working solution I gave you.

Mr. Expert 2021 29-Aug-21 8:29am

Even with your code it's not outputting anything

Richard MacCutchan 29-Aug-21 8:47am

No, because it is returning the values, True or False. If you want it to print something the change the last line to:

if found:
    print("True")
else:
    print("False")

Try and think carefully what you want the code to do at each step.

Mr. Expert 2021 29-Aug-21 20:58pm

Alright man

Mr. Expert 2021 29-Aug-21 8:11am

For example 2, 4, 5, and 7

Wendelius · Accepted Answer · 2021-08-28T21:13:00

Solution 1

Not sure if I understand your question correctly but if your trying to multiply, you're missing the asterisk.
So instead of

triangle = i(i + 1) / 2

try

triangle =  i * (i + 1) / 2

Posted 28-Aug-21 21:13pm

Wendelius

Comments

Mr. Expert 2021 29-Aug-21 3:28am

Alright that worked but when I enter 3 as my triangular number the output should be True not False. What can I do to make that happen?

Wendelius 29-Aug-21 3:42am

Try using the debugger. When you run the code line-by-line you'll notice that you enter the for loop only once, the value of i is 1 and the result for triangle is 1. So in the first iteration you compare 1 (i) to 3 (x) which is not equivalent and the program returns 3.

Having that said, you need to reconsider the loop so that you test all relevant positions and once done you decide if the number is triangular or not

Mr. Expert 2021 29-Aug-21 3:51am

Is it possible that you can provide me the code for that?

Wendelius 29-Aug-21 3:55am

In order to get to know a language, it's important that you try and experiment what happens with your code and when you change it.

For example try using the debugger and remove the elif section. Now when debugging, investigate the variables and see what happens.

Mr. Expert 2021 29-Aug-21 4:01am

Alright then.

Mr. Expert 2021 29-Aug-21 8:01am

def isTriangular(x):
"""Returns whether or not a given number x is triangular.

The triangular number Tn is a number that can be represented in the form of a triangular
grid of points where the first row contains a single element and each subsequent row contains
one more element than the previous one.

We can just use the fact that the nth triangular number can be found by using a formula: Tn = n(n + 1) / 2.

Example: 3 is triangular since 3 = 2(3) / 2
3 --> 2nd position: (2 * 3 / 2)

Example: 15 is triangular since 15 = 5(6) / 2
15 --> 5th position: (5 * 6 / 2)
"""

# your code here
i = 0
for i in range(1 + i, x + 1):
triangle = i * (i + 1) / 2
if triangle == x:
print("True")
elif i > triangle:
print("False")

isTriangular(24)

This is my updated code. Now it's all good but when I run a non-triangular number it doesn't return or print anything how can I make that happen?

Wendelius 29-Aug-21 8:26am

Because the way triangle is calculated, it's never less than i, so the elif section is never fired

One way to think about this is to let the loop find if the number is triangular and return if it is. If the loop is ran completely and triangular number is not found then return false.

Consider the following

def isTriangular(x):
    i = 0
    for i in range(1 + i, x + 1):
        triangle = i * (i + 1) / 2
        if triangle == x:
            return True
    return False

print(isTriangular(24))

Mr. Expert 2021 29-Aug-21 21:02pm

Got it. Can I call the function like "isTriangular(24)" because my grader expects it that way...

Wendelius 29-Aug-21 23:48pm

This was just a small example, you need to do any necessary changes for this to match the requirements you have.

Mr. Expert 2021 30-Aug-21 5:19am

How do I call the function I tried to do that but it did not return any output

Mr. Expert 2021 29-Aug-21 8:01am

triangular_numbers = [1, 3, 6, 10, 15, 21, 28, 36, 45, 55,
66, 78, 91, 105, 120, 136, 153, 171,
190, 210, 231]

not_triangular_numbers = [2, 4, 5, 7, 8, 9, 11, 12, 13, 14,
16, 17, 18, 19, 20,
22, 23, 24, 25, 26, 27,
29, 30, 31, 32, 33, 34, 35,
37, 40, 41, 42, 43, 44,
54, 56, 189, 191, 209, 211, 230, 232]