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TYPING: more type hints for io.formats.printing #27765

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Merged
merged 5 commits into from
Aug 23, 2019
Merged

TYPING: more type hints for io.formats.printing #27765

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TYPING: more type hints for io.formats.printing
simonjayhawkins Aug 5, 2019
53ef5c9
Merge remote-tracking branch 'upstream/master' into io.formats.printing
simonjayhawkins Aug 7, 2019
bff68be
use Any
simonjayhawkins Aug 7, 2019
5497eef
Merge remote-tracking branch 'upstream/master' into io.formats.printing
simonjayhawkins Aug 8, 2019
4f65722
Merge remote-tracking branch 'upstream/master' into io.formats.printing
simonjayhawkins Aug 23, 2019
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36 changes: 14 additions & 22 deletions pandas/io/formats/printing.py
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,8 @@

from pandas.core.dtypes.inference import is_sequence

EscapeChars = Union[Dict[str, str], Iterable[str]]


def adjoin(space: int, *lists: List[str], **kwargs) -> str:
"""
Expand Down Expand Up @@ -150,17 +152,14 @@ def _pprint_dict(
def pprint_thing(
thing,
_nest_lvl: int = 0,
escape_chars: Optional[Union[Dict[str, str], Iterable[str]]] = None,
escape_chars: Optional[EscapeChars] = None,
default_escapes: bool = False,
quote_strings: bool = False,
max_seq_items: Optional[int] = None,
) -> str:
"""
This function is the sanctioned way of converting objects
to a unicode representation.

properly handles nested sequences containing unicode strings
(unicode(object) does not)
to a string representation and properly handles nested sequences.

Parameters
----------
Expand All @@ -178,21 +177,13 @@ def pprint_thing(

Returns
-------
result - unicode str
str

"""

def as_escaped_unicode(thing, escape_chars=escape_chars):
# Unicode is fine, else we try to decode using utf-8 and 'replace'
# if that's not it either, we have no way of knowing and the user
# should deal with it himself.

try:
result = str(thing) # we should try this first
except UnicodeDecodeError:
# either utf-8 or we replace errors
result = str(thing).decode("utf-8", "replace")

def as_escaped_string(
thing: object, escape_chars: Optional[EscapeChars] = escape_chars
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Can you use Any instead of object? Won't change output since this is all green but would be more idiomatic

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Contrast the behavior of Any with the behavior of object. Similar to Any, every type is a subtype of object. However, unlike Any, the reverse is not true: object is not a subtype of every other type.

That means when the type of a value is object, a type checker will reject almost all operations on it, and assigning it to a variable (or using it as a return value) of a more specialized type is a type error.

Use object to indicate that a value could be any type in a typesafe manner. Use Any to indicate that a value is dynamically typed.

https://docs.python.org/3/library/typing.html#the-any-type

object is used here to indicate that a value could be any type in a typesafe manner and reject almost all operations on it.

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@simonjayhawkins simonjayhawkins Aug 7, 2019 •
edited
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In the outer function, thing should be Any since it is dynamically typed. we used hasattr and isinstance introspection. But following previous discussions, refraining from using Any and just leaving untyped.

) -> str:
translate = {"\t": r"\t", "\n": r"\n", "\r": r"\r"}
if isinstance(escape_chars, dict):
if default_escapes:
Expand All @@ -202,10 +193,11 @@ def as_escaped_unicode(thing, escape_chars=escape_chars):
escape_chars = list(escape_chars.keys())
else:
escape_chars = escape_chars or tuple()

result = str(thing)
for c in escape_chars:
result = result.replace(c, translate[c])

return str(result)
return result

if hasattr(thing, "__next__"):
return str(thing)
Expand All @@ -224,11 +216,11 @@ def as_escaped_unicode(thing, escape_chars=escape_chars):
max_seq_items=max_seq_items,
)
elif isinstance(thing, str) and quote_strings:
result = "'{thing}'".format(thing=as_escaped_unicode(thing))
result = "'{thing}'".format(thing=as_escaped_string(thing))
else:
result = as_escaped_unicode(thing)
result = as_escaped_string(thing)

return str(result) # always unicode
return result


def pprint_thing_encoded(
Expand Down