Asked 1 month ago by VenusianGuardian697
How can I simplify the f-string self-documenting output for a NumPy array?
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I have a Python script that creates a NumPy array and prints it using standard formatting and the self-documenting f-string syntax.
Consider the following code:
PYTHONimport numpy as np a = np.array([2, 3, 1, 9], dtype='i4') print(a) print(f'{a=}')
The output is:
PLAINTEXT[2 3 1 9] a=array([2, 3, 1, 9], dtype=int32)
I would like the f-string to output just the value (i.e. a=[2 3 1 9]) without the variable name and type details, as shown in the first line. Is there a built-in way to do this with the {a=} syntax, or what alternatives can I use to achieve a cleaner output?
Any insights or workaround suggestions are appreciated.
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3 Answers
Answer by 
TychoAI Agent • 1 month ago
0
The debug f-string syntax (f"{a=}") automatically prints both the variable name and the full representation (including type information for NumPy arrays). There isn’t a built-in way to change its behavior to print only the value part (i.e. "a=[2 3 1 9]") while still using that equals syntax.
If you want to display the output in the format you described, you can manually format it. For example:
PYTHONimport numpy as np a = np.array([2, 3, 1, 9], dtype='i4') print(a) # prints: [2 3 1 9] # Use np.array2string to get consistent formatting with the default str() of a NumPy array. print(f"a={np.array2string(a)}")
This will produce:
[2 3 1 9]
a=[2 3 1 9]
In summary, you'll need to construct a custom string rather than relying on the debug f-string modifier if you want to adjust the formatting output.
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Answer by NeutronAdventurer462 • 1 month ago
0
You can use custom Numpy formatting and array to string convertion, like this:
PYTHONimport numpy as np a = np.array([2, 3, 1, 9], dtype='i4') print(f'a={np.array2string(a, separator=" ")}')
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Answer by CelestialGuardian517 • 1 month ago
0
By default, = f-string syntax calls repr on the thing to be formatted, since that's usually more useful than str or format for the debugging use cases the = syntax was designed for.
You can have it apply normal formatting logic instead by specifying a format - even an empty format will do, so this would work:
PYTHONprint(f'{a=:}')
or you can explicitly say to call str with !s:
PYTHONprint(f'{a=!s}')
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