DEPR: read_table

[dahlbaek]

Went through #18262 looking for an easy task, and deprecating read_table looked like one. Currently, there's a function factory _make_parser_function which produces both read_csv and read_table here:

read_csv = _make_parser_function('read_csv', sep=',')
read_csv = Appender(_read_csv_doc)(read_csv)


read_table = _make_parser_function('read_table', sep='\t')
read_table = Appender(_read_table_doc)(read_table)

Seems to me the simplest solution is wrapping read_table like this:

def depr_read_table(func):
    """Deprecates read_table."""
    from functools import wraps
    @wraps(read_table)
    def depr_func(*args, **kwargs):
        if len(args) > 1 or "sep" in kwargs or "delimiter" in kwargs:
            warnings.warn("read_table is deprecated, use read_csv instead",
                          FutureWarning, stacklevel=2)
        else:
            warnings.warn("read_table is deprecated, use read_csv with "
                          "sep='\\t' instead",
                          FutureWarning, stacklevel=2)
        return func(*args, **kwargs)
    return depr_func
read_table = depr_read_table(read_table)

I would have to find out how to change the docs to declare the function deprecated, but I suppose that is easy...?

Result:

In [1]: import pandas as pd

In [2]: df = pd.DataFrame({"a": [1], "b": [2]})

In [3]: df.to_csv("test.csv", sep="\t")

In [4]: pd.read_table("test.csv", index_col=0)
/home/dahlbaek/virtualenvs/pandas-dev/bin/ipython:1: FutureWarning: read_table is deprecated, use read_csv with sep='\t' instead
  #!/home/dahlbaek/virtualenvs/pandas-dev/bin/python
Out[4]: 
   a  b
0  1  2

In [5]: pd.read_table("test.csv", "\t", index_col=0)
/home/dahlbaek/virtualenvs/pandas-dev/bin/ipython:1: FutureWarning: read_table is deprecated, use read_csv instead
  #!/home/dahlbaek/virtualenvs/pandas-dev/bin/python
Out[5]: 
   a  b
0  1  2

In [6]: pd.read_table("test.csv", sep="\t", index_col=0)
/home/dahlbaek/virtualenvs/pandas-dev/bin/ipython:1: FutureWarning: read_table is deprecated, use read_csv instead
  #!/home/dahlbaek/virtualenvs/pandas-dev/bin/python
Out[6]: 
   a  b
0  1  2

In [7]: pd.read_table("test.csv", delimiter="\t", index_col=0)
/home/dahlbaek/virtualenvs/pandas-dev/bin/ipython:1: FutureWarning: read_table is deprecated, use read_csv instead
  #!/home/dahlbaek/virtualenvs/pandas-dev/bin/python
Out[7]: 
   a  b
0  1  2

In [8]: df
Out[8]: 
   a  b
0  1  2

Any thoughts?

[dahlbaek]

I suppose declaring the function deprecated could be as simple as changing _read_table_doc here into

_read_table_doc = """
.. deprecated:: 0.24.0
   Use :func:`pandas.read_csv` instead, passing `sep='\t'` if necessary.

Read general delimited file into DataFrame
%s
""" % (_parser_params % (_sep_doc.format(default="\\t (tab-stop)"),
                         _engine_doc))```

[gfyoung]

I would consider adding another parameter to _make_parser_function so that it adds the appropriate deprecation messages both in the code and in the docstring.

[st-bender]

Why not deprecate read_csv() instead? read_table() sounds more general and if they are basically the same, why not keep both as aliases?