# Which is the smallest dataset included with MNE \` mne.datasets\` (testing purposes)

**URL:** <https://mne.discourse.group/t/which-is-the-smallest-dataset-included-with-mne-mne-datasets-testing-purposes/8754>\
**Category:** Support & Discussions\
**Created:** [May 5, 2024, 10:08pm UTC](https://mne.discourse.group/t/which-is-the-smallest-dataset-included-with-mne-mne-datasets-testing-purposes/8754 "2024-05-05T22:08:29Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![danieltomasz](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/danieltomasz/32/101_2.png) [@danieltomasz](https://mne.discourse.group/u/danieltomasz)\
**Post date:** [May 5, 2024, 10:08pm UTC](https://mne.discourse.group/t/which-is-the-smallest-dataset-included-with-mne-mne-datasets-testing-purposes/8754/1 "2024-05-05T22:08:29Z")

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What is the smallest dataset that could be downloaded? Sometimes I need to create an example to reproduce or demontrate some issue that is not related to specific dataset (or fairly general), for example an problem with plotting, and I want to use some of the datasets inluded with `mne.datasets` but I don’t know its size.

I would like to limit my carbon footprint/ time used to download data (and pick the smallest dataset that I can use to test my problem)

Could this information, at least for some of the smallest/most used dataset be provided at the relevant page?  
[https://mne.tools/dev/documentation/datasets.html](https://mne.tools/dev/documentation/datasets.html)

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**Author:** ![cbrnr](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/cbrnr/32/1409_2.png) [@cbrnr](https://mne.discourse.group/u/cbrnr)\
**Post date:** [May 6, 2024, 4:39am UTC](https://mne.discourse.group/t/which-is-the-smallest-dataset-included-with-mne-mne-datasets-testing-purposes/8754/2 "2024-05-06T04:39:45Z")

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I don’t know off the top of my hat, but this information would be very valuable to have in the docs!

Often you probably don’t even need to download real EEG to demonstrate the problem, so here’s what I usually use in my examples:

```python
from mne import create_info
from mne.io import RawArray
from numpy.random import default_rng

def create_toy_data(n_channels=3, duration=25, sfreq=250, seed=None):
    rng = default_rng(seed)
    data = rng.standard_normal(size=(n_channels, duration * sfreq)) * 5e-6
    info = create_info(n_channels, sfreq, "eeg")
    return RawArray(data, info)

raw = create_toy_data()

```

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**Author:** ![richard](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/richard/32/15_2.png) [@richard](https://mne.discourse.group/u/richard)\
**Post date:** [May 6, 2024, 6:32am UTC](https://mne.discourse.group/t/which-is-the-smallest-dataset-included-with-mne-mne-datasets-testing-purposes/8754/3 "2024-05-06T06:32:08Z")

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Time to start addressing [Function for creating toy data · Issue #10954 · mne-tools/mne-python · GitHub](https://github.com/mne-tools/mne-python/issues/10954) 🥲