Add optional column separator character to DataFrame.to_string()

[dov]

I'd like more flexibility in the stringification of a pandas dataframe. Consider a trivial dataframe:

import pandas as pd

df = pd.DataFrame([[1.2454235445,2],
                   [3,4.452455]],
                   columns = ['A','B'])
print(df.to_string())

This outputs:

          A         B
0  1.245424  2.000000
1  3.000000  4.452455

My desired output is:

|   |       A  |       B  |
+---+----------+----------+
| 0 | 1.245424 | 2.000000 |
| 1 | 3.000000 | 4.452455 |

I suggest adding the following options to to_string() to support the above output:

• output_column_separator -- The vertical bar in the above example
• output_row_separator -- The hyphen in the above example
• output_cross_separator -- The plus sign in the above example

[jreback]

why?

[dov]

Because I often find myself copying a pandas dataframe output into an org-mode document, and there is no simple way of 1) using the float formatting preference of DataFrame.to_string() and 2) inserting the table delimiters. But more generally, I think that the stringified DataFrame is a matter of preference, just as a html'ified dataframe is styled according to preference.

[jreback]

see discussion and links here: #11052