[Pandas-dev] Proposal to change the default number of rows for DataFrame display (lower max_rows)

[Joris Van den Bossche]

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Hi all,

I am reposting the mail of Clemens below, but with slightly changed focus,
as I think the main discussion point is about the number of rows.

The proposal in https://github.com/pandas-dev/pandas/pull/17023 is to lower
the default number of rows shown when displaying a Series or DataFrame from
60 to 20.

Thoughts on that?

Best,
Joris


2017-11-28 11:57 GMT+01:00 Clemens Brunner <clemens.brunner at gmail.com>:

> Hello!
>
> We're currently discussing a change in how data frames are displayed by
> default in https://github.com/pandas-dev/pandas/pull/17023. There are two
> proposed changes:
>
> (1) Set pd.options.display.max_columns=0 (previously this was set to 20).
> (2) Set pd.options.display.max_rows=20 (previously this was set to 60).
>
> Change (1) means that the number of printed columns is adapted to fit
> within the width of the terminal. If there are too many columns, ellipsis
> will be shown to indicate collapsed columns in the middle of the data
> frame. This doesn't work if Python is run as a Jupyter kernel (e.g. in a
> Jupyter notebook or in IPython QtConsole), in which case the maximum
> columns remain 20.
>
> Example:
> ========
> import pandas as pd
> import numpy as np
> pd.DataFrame(np.random.rand(5, 10))
>
> Output before (in a terminal with 100 chars width):
> ---------------------------------------------------
>           0         1         2         3         4         5         6  \
> 0  0.643979  0.690414  0.018603  0.991478  0.707534  0.376765  0.670848
> 1  0.547836  0.810972  0.054448  0.415112  0.268120  0.904528  0.839258
> 2  0.582256  0.732149  0.284208  0.405197  0.213591  0.715367  0.150106
> 3  0.197348  0.317159  0.051669  0.738405  0.821046  0.179270  0.245793
> 4  0.483466  0.583330  0.999213  0.882883  0.315169  0.045712  0.897048
>
>           7         8         9
> 0  0.891467  0.494220  0.713369
> 1  0.601304  0.449880  0.266205
> 2  0.113262  0.360580  0.238833
> 3  0.798063  0.077769  0.471169
> 4  0.262779  0.530565  0.992084
>
> Output after:
> -------------
>           0         1         2         3    ...            6         7
>      8         9
> 0  0.673621  0.211505  0.943201  0.946548    ...     0.900453  0.612182
> 0.861933  0.710967
> 1  0.670855  0.834449  0.796273  0.785976    ...     0.609954  0.686663
> 0.684582  0.837505
> 2  0.544736  0.814827  0.352893  0.459556    ...     0.650993  0.735943
> 0.279110  0.840203
> 3  0.440125  0.554323  0.745462  0.940896    ...     0.544576  0.224175
> 0.852603  0.509837
> 4  0.225551  0.791834  0.476059  0.321857    ...     0.391165  0.423213
> 0.290683  0.954423
>
> [5 rows x 10 columns]
>
>
> Change (2) implies fewer rows are displayed before auto-hiding takes
> place. I find that 60 rows almost always causes the terminal to scroll
> (most terminals have between 25-40 rows), so reducing the value to 20
> increases the chance that a data frame can be observed on one terminal
> page. I'm not including a before/after output since it should be easy to
> imagine how this change affects the output.
>
> Both changes would make Pandas behave similar to R's Tidyverse (which I
> really like), but this should not be the main reason why these changes are
> a good idea. I mainly like them because these settings make (large) data
> frames much nicer to look at.
>
> Note that these changes affect the default values. Of course, users are
> free to change them back in their active Python session.
>
> Comments to both proposed changes are highly welcome (either here on the
> mailing list or at https://github.com/pandas-dev/pandas/pull/17023.
>
> Clemens
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>
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