Why do I get the syntax error "SyntaxError: invalid syntax" in a line with perfectly valid syntax?

Question

I have this code:

def Psat(self, T):
    pop= self.getPborder(T)
    boolean=int(pop[0])
   
    P1=pop[1]
    P2=pop[2]
    if boolean:
        Pmin = float(min([P1, P2]))
        Pmax = float(max([P1, P2]))
        Tr=T/self.typeMolecule.Tc
        w=0.5*(1+scipy.tanh((10**5)*(Tr-0.6)))
        fi1=0.5*(1-scipy.tanh(8*((Tr**0.4)-1)))
        fi2=0.460*scipy.sqrt(1-(Tr-0.566)**2/(0.434**2)+0.494

        guess = Pmin+(Pmax-Pmin)*((1-w**2)*fi1+(w**2)*fi2)   # error here
    
        solution = scipy.optimize.newton(funcPsat,guess, args=(T,self))

On the marked line of code, guess = Pmin+(Pmax-Pmin)*((1-w**2)*fi1+(w**2)*fi2), I get an error message: SyntaxError: invalid syntax.

Pmin, Pmax, w, fi1 and fi2 have all been assigned at this point, so why is there an error?

When I remove that line from the code, the same error appears at the next line of code, again for no apparent reason.

Asked By: Pearl Philip

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Source

Answer 1

When an error is reported on a line that appears correct, try removing (or commenting out) the line where the error appears to be. If the error moves to the next line, there are two possibilities:

Either both lines have a problem (and the second may have been hidden by the first); or
The previous line has a problem which is being carried forward.

The latter is more likely, especially if removing another line causes the error to move again.

For example, code like the following, saved as twisty_passages.py:

xyzzy = (1 +
plugh = 7

will produce an error on line 2, even though the problem is clearly caused by line 1:

  File "twisty_passages.py", line 2
    plugh = 7
          ^
SyntaxError: invalid syntax

The code in the question has a similar problem: the code on the previous line has unbalanced parentheses. Annotated to make it clearer:

# open parentheses: 1  2             3
#                   v  v             v
fi2=0.460*scipy.sqrt(1-(Tr-0.566)**2/(0.434**2)+0.494
#                               ^             ^
# close parentheses:            1             2

There isn’t really a general solution for this – the code needs to be analyzed and understood, in order to determine how the parentheses should be altered.

Answered By: paxdiablo

Answer 2

You’re missing a close paren in this line:

fi2=0.460*scipy.sqrt(1-(Tr-0.566)**2/(0.434**2)+0.494

There are three ( and only two ).

Answered By: aaron newland

Answer 3

I encountered a similar problem, with a syntax error that I knew should not be a syntax error. In my case it turned out that a Python 2 interpreter was trying to run Python 3 code, or vice versa; I think that my shell had a PYTHONPATH with a mixture of Python 2 and Python 3.

Answered By: jbyler

Answer 4

I noticed that invalid syntax error for no apparent reason can be caused by using space in:

print(f'{something something}')

Python IDLE seems to jump and highlight a part of the first line for some reason (even if the first line happens to be a comment), which is misleading.

Answered By: michalmonday

Why do I get the syntax error "SyntaxError: invalid syntax" in a line with perfectly valid syntax?

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