Name error with f-strings in python3

Question

I am using the following f-strings in a web application. When I run it locally (before trying on the web) I am getting a name error:

NameError: name 'path' is not defined

But path prints properly and seems to be defined to my mind. What am I doing wrong?

path = f'{PROJECT_PATH["raw_data"]}/cashValues'
print("PATH", path)
filenames = [f'{path}/{i}' for i in filenames]

Thanks

Full traceback:

Traceback (most recent call last):
  File "scripts/TableTransform.py", line 8, in <module>
    class TableTransform(object):
  File "scripts/TableTransform.py", line 14, in TableTransform
    Filenames = [f'{path}/{i}' for i in filenames]
  File "scripts/TableTransform.py", line 14, in <listcomp>
    Filenames = [f'{path}/{i}' for i in filenames]
NameError: name 'path' is not defined

Can't reproduce the problem with the information given. Assuming `PROJECT_PATH` and `filenames` are properly defined, this shouldn't give any errors. If you actually run just these three lines after setting reasonable values for those, do you actually still get the error? — glibdud, Jul 18 '18 at 12:28
Are you sure the error is happening here? Can you provide the full traceback? — glibdud, Jul 18 '18 at 12:29
Yes its super odd. I cannot think why. As mentioned the print statement prints out the path exactly as I expect it to with the correct value. The path is correctly specified. I added the full traceback — Woody Pride, Jul 18 '18 at 13:20
Sorry, yes that worked nicely! It just needed some "" around "raw_data" — Woody Pride, Jul 18 '18 at 13:21
what is `cashValues`.? A variable name.? or name of a folder.? — Sreeram TP, Jul 18 '18 at 13:24
Sorry no that did not work, all that does is set the path as "path" — Woody Pride, Jul 18 '18 at 13:28
It works when I enter it directly into ipython but does not work when i run the whole script — Woody Pride, Jul 18 '18 at 17:01
It does not work when I do this either `[os.path.join(path, i) for i in filenames]` — Woody Pride, Jul 18 '18 at 17:10

score 0 · Answer 1 · answered Jul 18 '18 at 17:36

0

It seems that list comprehension in python 3.6.5 has its own scope and is not aware of variables outside of that scope. This is why it was failing.

answered Jul 18 '18 at 17:36

Woody Pride

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Name error with f-strings in python3

1 Answers1