Can't pd.options.display.max_columns = 0 by default?

[cbrnr]

pd.options.display.max_columns is 20 by default, but when running in a terminal this value could be auto-detected by setting it to 0. I know that this setting can be customized, but for the average user it would be much more convenient if there was no extra step involved. Is there a way to detect if pandas is running in a terminal (where autodetection works)? If so, the value should be set to 0. Otherwise, for example in Jupyter notebooks, it could remain to be 20.

[jreback]

Say you auto-detect (via get_terminal_size) and its 80, then what, how many columns should it be?

This is a pretty reasonable default.

[cbrnr]

Maybe I wasn't clear. If the width gets autodetected, a much more reasonable choice for max_columns would be 0. That way, the printed object would fit within the terminal width.

[cbrnr]

@jreback could you reconsider this? Here's an example to show what I mean:

import numpy as np
import pandas as pd
pd.DataFrame(np.random.rand(5, 10))

In a terminal (mine has 100 columns), the default output of this dataframe looks like this:

          0         1         2         3         4         5         6  \
0  0.173421  0.463432  0.829303  0.557628  0.257765  0.712062  0.129705   
1  0.113790  0.310267  0.076708  0.576933  0.562503  0.623521  0.002787   
2  0.628581  0.740680  0.327314  0.129068  0.816575  0.470844  0.771247   
3  0.947981  0.984844  0.113195  0.449247  0.494137  0.349844  0.207327   
4  0.087635  0.678417  0.255774  0.924561  0.597169  0.089508  0.650698   

          7         8         9  
0  0.817547  0.337570  0.348707  
1  0.051971  0.983914  0.972759  
2  0.566701  0.627593  0.126499  
3  0.619493  0.292824  0.653050  
4  0.530746  0.773546  0.496640  

Now if I set pd.options.display.max_columns = 0, the output looks much nicer:

         0         1         2         3     ...           16        17        18        19
0  0.238365  0.438112  0.307173  0.226128    ...     0.547763  0.319377  0.688708  0.840808
1  0.153844  0.472930  0.128777  0.197224    ...     0.533801  0.530466  0.417650  0.174715
2  0.964627  0.626036  0.433339  0.834303    ...     0.036854  0.248769  0.932532  0.669207
3  0.375633  0.581266  0.026618  0.394931    ...     0.049323  0.195138  0.502164  0.454383
4  0.799988  0.137955  0.067402  0.012556    ...     0.587728  0.226844  0.447049  0.117987

So I was wondering why pd.options.display.max_columns can't be 0 by default?

[jreback]

@TomAugspurger ?

[TomAugspurger]

I usually set the max columns to 0 in my IPython init. I think it would be ok to change the default.

Do we still run into issues where we can't reliably detect the terminal width, or have those all been fixed?

[cbrnr]

I'll create a PR so that this stays on the radar. I'd also like to propose to change pd.options.display.max_rows to 20 instead of 60, because ideally I'd like to see a summary of the data frame including the column names. This is also how tibbles in R are displayed BTW.

[cbrnr]

Regarding the detection of the terminal width, I think it doesn't work in PyCharm's integrated terminal. However, the default of 80 is a reasonable value in this case.