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<h1>Dask</h1>
<h2 id="how-to-install">How to install</h2>
<p><a href="https://dask.org">Dask</a> also supports Apache ORC.</p>
<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>pip3 install "dask[dataframe]==2025.5.1"
pip3 install pandas
</code></pre></div></div>
<h2 id="how-to-write-and-read-an-orc-file">How to write and read an ORC file</h2>
<div class="language-plaintext highlighter-rouge"><div class="highlight"><pre class="highlight"><code>In [1]: import pandas as pd
In [2]: import dask.dataframe as dd
In [3]: pf = pd.DataFrame(data={"col1": [1, 2, 3], "col2": ["a", "b", None]})
In [4]: dd.to_orc(dd.from_pandas(pf, npartitions=2), path="/tmp/orc")
Out[4]: (None, None)
In [5]: dd.read_orc(path="/tmp/orc").compute()
Out[5]:
col1 col2
0 1 a
1 2 b
0 3 &lt;NA&gt;
In [6]: dd.read_orc(path="/tmp/orc", columns=["col1"]).compute()
Out[6]:
col1
0 1
1 2
0 3
</code></pre></div></div>
<p><a href="https://docs.dask.org/en/stable/10-minutes-to-dask.html">10 Minutes to Dask</a> page
provides a short overview.</p>
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