Python Forum

I got this error of unsupported format character, As shown:

Output:
ValueError                                Traceback (most recent call last)
Input In [6], in <cell line: 6>()
      4 pq = np.sum(p * np.log(p/q))
      5 qp = np.sum(q * np.log(q/p))
----> 6 print('KL(P || Q) : %. pq)%.3f' % pq)
      7 print('KL(Q || P) : %. pq)%.3f' % qp)

ValueError: unsupported format character ' ' (0x20) at index 15

I do not see it. Could it be a space before the colon? It calls it on the first
print line. I am guessing it would also call it on the second print line if it ever got there.

Help appreciated.

Respectfully,

LZ

No, the unsupported format character is not it. I just tried removing the space before the colon It still calls an error. Unsupported
format character.

R,

LZ

The error is exactly where the error message says.

Error:
KL(P || Q) : %. pq)%.3f
               ^Here's the error, right at index 15 in the format string

Python is looking for a format character to associate with the first "%". It will grab whatever comes next. So the problem is that you have an unsupported format character (space)

I'm not sure what you are trying to do here. It is a bit of a mess.

print('KL(P || Q) : %. pq)%.3f' % pq)

Since there is only one variable to print there can only be one % in the format string. The first % is incorrect.

Did you want this?

print("KL(P || Q) : %% pq)%.3f" % pq)

Output:
KL(P || Q) : % pq)10.123

or this?

print("KL(P || Q) : %.3f pq)" % pq)

Output:
KL(P || Q) : 10.123 pq)

or maybe

print("KL(P || Q) : %.3f" % pq)

Output:
KL(P || Q) : 10.123

Modulo string formatting is ancient and has been replaced (twice!). f'string formatting is much easier to understand.

print(f"KL(P || Q) : {pq:.3}"

With f'string formatting the variables appear inside the string, in the same spot they will appear in the final string. Modulo (%) and format() style formatting had the variables appear at the end where it was easy to mess up the order. I also like the clear demarkation the curly brackets provide, separating formatting from the rest of the string.