title: How to convert pandas.DataFrame to datatable.Frame containing Int32 (nullable integer)?
body: <p>I have a <a href="https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.html" rel="nofollow noreferrer"><code>pandas.DataFrame</code></a> containing <a href="https://pandas.pydata.org/pandas-docs/stable/user_guide/integer_na.html" rel="nofollow noreferrer">pandas nullable integer data type</a> and want to convert it to an equivalent <a href="https://datatable.readthedocs.io/en/latest/api/frame.html" rel="nofollow noreferrer"><code>datatable.Frame</code></a> object. However it seems it is not directly possible. What is the best way of doing the conversion without breaking stuff? I do not have the DataFrames available in text form, but they com e from a <code>pickle</code>. MWE:</p>
  <pre class="lang-py prettyprint-override"><code>import numpy as np, pandas as pd, datatable as dt
  vec = [0,1,2, np.nan]
  df = pd.DataFrame(vec, dtype=&quot;Int32&quot;)
  frame = dt.Frame(vec, stypes=[&quot;int32&quot;])   # works fine
  dt.Frame(df)   # raises error
  # TypeError: Cannot create a column from &lt;class 'pandas.core.arrays.integer.IntegerArray'&gt;
  </code></pre>