Saving Pandas dataframe indices to file
<p>I am trying to save just the indices of a dataframe to a file. Here is what I've tried:</p>

<p>A)</p>

<pre><code>np.savetxt("file_name", df.index.values)
</code></pre>

<p>returns:</p>

<pre><code>TypeError: Mismatch between array dtype ('object') and format specifier ('%.18e')
</code></pre>

<p>B)</p>

<pre><code>df.index.values.tofile("file_name")
</code></pre>

<p>returns:</p>

<pre><code>IOError: cannot write object arrays to a file in binary mode
</code></pre>

<p>C) </p>

<pre><code>with open("file_name","w") as f:
    f.write("\n".join(df_1_indexes.values.tolist()))
</code></pre>

<p>Can someone please explain why A) and B) failed? I'm at a loss. </p>

<p>Cheers</p>