: [3, 4]}
df = pd.DataFrame(data=d)
df
   col1  col2
0     1     3
1     2     4</p>
</blockquote>
</blockquote>
</blockquote>
<p>Notice that the inferred dtype is int64.</p>
<blockquote><blockquote><blockquote><p>df.dtypes
col1    int64
col2    int64
dtype: object</p>
</blockquote>
</blockquote>
</blockquote>
<p>To enforce a single dtype:</p>
<blockquote><blockquote><blockquote><p>df = pd.DataFrame(data=d, dtype=np.int8)
df.dtypes
col1    int8
col2    int8
dtype: object</p>
</blockquote>
</blockquote>
</bl