python 3.8.0 – print self-documenting expression with value of variable on a new line

Question

Python 3.8.0 allows for self-documenting expressions and debugging using =, e.g.: print(f'{myvar=}').

Is it possible to print the output on a new line? this would be useful for variables with multi-line outputs like dataframes.

e.g.

>>> df = pd.DataFrame({'animal':['alligator', 'bee', 'falcon', 'lion',
                  'monkey', 'parrot', 'shark', 'whale', 'zebra']})

>>> print(f'{df.head()=}')
df.head() =
    animal
0  alligator
1        bee
2     falcon
3       lion
4     monkey

Asked By: John

||

Source

Answer 1

If you make your f string triple-quoted, you can include a newline after the =:

df = pd.DataFrame({'animal':['alligator', 'bee', 'falcon', 'lion',
                  'monkey', 'parrot', 'shark', 'whale', 'zebra']})

print(f'''{df=
}''')

Answered By: Patrick Haugh

Answer 2

Using triple quotes works, but it causes some trouble when the print statement is in an indented block:

if True:
    if True:
        # ...some code with indentation...
        print(f"""{df =
}""")
        # ...more code with indentation...

Note that one does not simply indent the }""" part to the proper level, without breaking the formatting of the first line of the f-string.

I asked a similar question, and found a single line solution here, which I am writing here as well, for reference.

df = pd.DataFrame({'animal':['alligator', 'bee', 'falcon', 'lion',
                  'monkey', 'parrot', 'shark', 'whale', 'zebra']})

f_str_nl = lambda object: f"{chr(10) + str(object)}"  # add n directly
# f_str_nl = lambda object: f"{os.linesep + str(object)}"  # add rn on windows

print(f"{f_str_nl(df) = !s}")

which outputs:

f_str_nl(df) = 
      animal
0  alligator
1        bee
2     falcon
3       lion
4     monkey
5     parrot
6      shark
7      whale
8      zebra

This method does not cause problems with indented blocks.
However, the name of the object in the f-string gets wrapped with the function name, f_str_nl().

Answered By: Enigma Machine

python 3.8.0 – print self-documenting expression with value of variable on a new line

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