<p dir="auto">See this <a href="http://stackoverflow.com/a/16613835/1240268" rel="nofollow">SO question</a>:</p>
<p dir="auto">Apparently (for a DataFrame with DatetimeIndex) drop requires a Timestamp object (this is different from ix/loc which can cunningly work out you meant a timestamp, if fed a string).</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="In [11]: df1
Out[11]:
                     Price1  Price2  Price3
Date_Time
2012-01-01 00:00:00   63.05   41.40   68.14
2012-01-01 01:00:00   68.20   42.44   59.64
2012-01-01 02:00:00   61.68   43.18   49.81

In [12]: df1.drop(pd.Timestamp('2012-01-01 01:00:00'))
Out[12]:
                     Price1  Price2  Price3
Date_Time
2012-01-01 00:00:00   63.05   41.40   68.14
2012-01-01 02:00:00   61.68   43.18   49.81

In [13]: df1.drop('2012-01-01 01:00:00')
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
&lt;ipython-input-13-334d00239c8b&gt; in &lt;module&gt;()
----&gt; 1 df1.drop('2012-01-01 01:00:00')

/Users/234BroadWalk/pandas/pandas/core/generic.pyc in drop(self, labels, axis, level)
    373                 new_axis = axis.drop(labels, level=level)
    374             else:
--&gt; 375                 new_axis = axis.drop(labels)
    376             dropped = self.reindex(**{axis_name: new_axis})
    377             try:

/Users/234BroadWalk/pandas/pandas/core/index.pyc in drop(self, labels)
   1296         mask = indexer == -1
   1297         if mask.any():
-&gt; 1298             raise ValueError('labels %s not contained in axis' % labels[mask])
   1299         return self.delete(indexer)
   1300

ValueError: labels ['2012-01-01 01:00:00'] not contained in axis"><pre class="notranslate"><code class="notranslate">In [11]: df1
Out[11]:
                     Price1  Price2  Price3
Date_Time
2012-01-01 00:00:00   63.05   41.40   68.14
2012-01-01 01:00:00   68.20   42.44   59.64
2012-01-01 02:00:00   61.68   43.18   49.81

In [12]: df1.drop(pd.Timestamp('2012-01-01 01:00:00'))
Out[12]:
                     Price1  Price2  Price3
Date_Time
2012-01-01 00:00:00   63.05   41.40   68.14
2012-01-01 02:00:00   61.68   43.18   49.81

In [13]: df1.drop('2012-01-01 01:00:00')
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
&lt;ipython-input-13-334d00239c8b&gt; in &lt;module&gt;()
----&gt; 1 df1.drop('2012-01-01 01:00:00')

/Users/234BroadWalk/pandas/pandas/core/generic.pyc in drop(self, labels, axis, level)
    373                 new_axis = axis.drop(labels, level=level)
    374             else:
--&gt; 375                 new_axis = axis.drop(labels)
    376             dropped = self.reindex(**{axis_name: new_axis})
    377             try:

/Users/234BroadWalk/pandas/pandas/core/index.pyc in drop(self, labels)
   1296         mask = indexer == -1
   1297         if mask.any():
-&gt; 1298             raise ValueError('labels %s not contained in axis' % labels[mask])
   1299         return self.delete(indexer)
   1300

ValueError: labels ['2012-01-01 01:00:00'] not contained in axis
</code></pre></div>
<p dir="auto">Compare to ix/iloc which don't care:</p>
<div class="snippet-clipboard-content notranslate position-relative overflow-auto" data-snippet-clipboard-copy-content="In [21]: df1.loc['2012-01-01 01:00:00']
Out[21]:
Price1    68.20
Price2    42.44
Price3    59.64
Name: 2012-01-01 01:00:00, dtype: float64

In [22]: df1.loc[pd.Timestamp('2012-01-01 01:00:00')]
Out[22]:
Price1    68.20
Price2    42.44
Price3    59.64
Name: 2012-01-01 01:00:00, dtype: float64"><pre class="notranslate"><code class="notranslate">In [21]: df1.loc['2012-01-01 01:00:00']
Out[21]:
Price1    68.20
Price2    42.44
Price3    59.64
Name: 2012-01-01 01:00:00, dtype: float64

In [22]: df1.loc[pd.Timestamp('2012-01-01 01:00:00')]
Out[22]:
Price1    68.20
Price2    42.44
Price3    59.64
Name: 2012-01-01 01:00:00, dtype: float64
</code></pre></div>
<p dir="auto"><em>Perhaps worth investigating where else this could work/not.</em></p>
<p dir="auto">Needs to coerce:</p>
<p dir="auto">e.g.</p>
<div class="highlight highlight-source-python notranslate position-relative overflow-auto" dir="auto" data-snippet-clipboard-copy-content="In [1]: import pandas.util.testing as tm

In [2]: pan = tm.makePanel()

In [3]: pan
Out[3]:
&lt;class 'pandas.core.panel.Panel'&gt;
Dimensions: 3 (items) x 30 (major_axis) x 4 (minor_axis)
Items axis: ItemA to ItemC
Major_axis axis: 2000-01-03 00:00:00 to 2000-02-11 00:00:00
Minor_axis axis: A to D

In [4]: pan.drop('2000-01-03', axis=1)
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
&lt;ipython-input-4-11e47d7c99f1&gt; in &lt;module&gt;()
----&gt; 1 pan.drop('2000-01-03', axis=1)

../pandas/core/generic.pyc in drop(self, labels, axis, level)
   1112                 new_axis = axis.drop(labels, level=level)
   1113             else:
-&gt; 1114                 new_axis = axis.drop(labels)
   1115             dropped = self.reindex(**{ axis_name: new_axis })
   1116             try:

../pandas/core/index.pyc in drop(self, labels)
   1614         mask = indexer == -1
   1615         if mask.any():
-&gt; 1616             raise ValueError('labels %s not contained in axis' % labels[mask])
   1617         return self.delete(indexer)
   1618

ValueError: labels ['2000-01-03'] not contained in axis"><pre class="notranslate"><span class="pl-v">In</span> [<span class="pl-c1">1</span>]: <span class="pl-s1">import</span> <span class="pl-s1">pandas</span>.<span class="pl-s1">util</span>.<span class="pl-s1">testing</span> <span class="pl-k">as</span> <span class="pl-s1">tm</span>

<span class="pl-v">In</span> [<span class="pl-c1">2</span>]: <span class="pl-s1">pan</span> <span class="pl-c1">=</span> <span class="pl-s1">tm</span>.<span class="pl-en">makePanel</span>()

<span class="pl-v">In</span> [<span class="pl-c1">3</span>]: <span class="pl-s1">pan</span>
<span class="pl-v">Out</span>[<span class="pl-c1">3</span>]:<span class="pl-s1"></span>
<span class="pl-c1">&lt;</span><span class="pl-s1">class</span> <span class="pl-s">'pandas.core.panel.Panel'</span><span class="pl-c1">&gt;</span>
<span class="pl-v">Dimensions</span>: <span class="pl-c1">3</span> (<span class="pl-s1">items</span>) <span class="pl-s1">x</span> <span class="pl-c1">30</span> (<span class="pl-s1">major_axis</span>) <span class="pl-s1">x</span> <span class="pl-c1">4</span> (<span class="pl-s1">minor_axis</span>)
<span class="pl-v">Items</span> <span class="pl-s1">axis</span>: <span class="pl-v">ItemA</span> <span class="pl-s1">to</span> <span class="pl-v">ItemC</span>
<span class="pl-v">Major_axis</span> <span class="pl-s1">axis</span>: <span class="pl-c1">2000</span><span class="pl-c1">-</span><span class="pl-c1">01</span><span class="pl-c1">-</span><span class="pl-c1">03</span> <span class="pl-c1">00</span>:<span class="pl-c1">00</span>:<span class="pl-c1">00</span> <span class="pl-s1">to</span> <span class="pl-c1">2000</span><span class="pl-c1">-</span><span class="pl-c1">02</span><span class="pl-c1">-</span><span class="pl-c1">11</span> <span class="pl-c1">00</span>:<span class="pl-c1">00</span>:<span class="pl-c1">00</span>
<span class="pl-v">Minor_axis</span> <span class="pl-s1">axis</span>: <span class="pl-v">A</span> <span class="pl-s1">to</span> <span class="pl-v">D</span>

<span class="pl-v">In</span> [<span class="pl-c1">4</span>]: <span class="pl-s1">pan</span>.<span class="pl-en">drop</span>(<span class="pl-s">'2000-01-03'</span>, <span class="pl-s1">axis</span><span class="pl-c1">=</span><span class="pl-c1">1</span>)
<span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span>
<span class="pl-v">ValueError</span>                                <span class="pl-v">Traceback</span> (<span class="pl-s1">most</span> <span class="pl-s1">recent</span> <span class="pl-s1">call</span> <span class="pl-s1">last</span>)
<span class="pl-c1">&lt;</span><span class="pl-s1">ipython</span><span class="pl-c1">-</span><span class="pl-s1">input</span><span class="pl-c1">-</span><span class="pl-c1">4</span><span class="pl-c1">-</span><span class="pl-c1">11e47</span><span class="pl-s1">d7c99f1</span><span class="pl-c1">&gt;</span> <span class="pl-s1">in</span> <span class="pl-c1">&lt;</span><span class="pl-s1">module</span><span class="pl-c1">&gt;</span>()
<span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">-</span><span class="pl-c1">&gt;</span> <span class="pl-c1">1</span> <span class="pl-s1">pan</span>.<span class="pl-en">drop</span>(<span class="pl-s">'2000-01-03'</span>, <span class="pl-s1">axis</span><span class="pl-c1">=</span><span class="pl-c1">1</span>)

..<span class="pl-c1">/</span><span class="pl-s1">pandas</span><span class="pl-c1">/</span><span class="pl-s1">core</span><span class="pl-c1">/</span><span class="pl-s1">generic</span>.<span class="pl-s1">pyc</span> <span class="pl-c1">in</span> <span class="pl-en">drop</span>(<span class="pl-s1">self</span>, <span class="pl-s1">labels</span>, <span class="pl-s1">axis</span>, <span class="pl-s1">level</span>)
   <span class="pl-c1">1112</span>                 <span class="pl-s1">new_axis</span> <span class="pl-c1">=</span> <span class="pl-s1">axis</span>.<span class="pl-en">drop</span>(<span class="pl-s1">labels</span>, <span class="pl-s1">level</span><span class="pl-c1">=</span><span class="pl-s1">level</span>)
   <span class="pl-c1">1113</span>             <span class="pl-s1">else</span>:
<span class="pl-c1">-</span><span class="pl-c1">&gt;</span> <span class="pl-c1">1114</span>                 <span class="pl-s1">new_axis</span> <span class="pl-c1">=</span> <span class="pl-s1">axis</span>.<span class="pl-en">drop</span>(<span class="pl-s1">labels</span>)
   <span class="pl-c1">1115</span>             <span class="pl-s1">dropped</span> <span class="pl-c1">=</span> <span class="pl-s1">self</span>.<span class="pl-en">reindex</span>(<span class="pl-c1">**</span>{ <span class="pl-s1">axis_name</span>: <span class="pl-s1">new_axis</span> })
   <span class="pl-c1">1116</span>             <span class="pl-k">try</span>:

..<span class="pl-c1">/</span><span class="pl-s1">pandas</span><span class="pl-c1">/</span><span class="pl-s1">core</span><span class="pl-c1">/</span><span class="pl-s1">index</span>.<span class="pl-s1">pyc</span> <span class="pl-c1">in</span> <span class="pl-en">drop</span>(<span class="pl-s1">self</span>, <span class="pl-s1">labels</span>)
   <span class="pl-c1">1614</span>         <span class="pl-s1">mask</span> <span class="pl-c1">=</span> <span class="pl-s1">indexer</span> <span class="pl-c1">==</span> <span class="pl-c1">-</span><span class="pl-c1">1</span>
   <span class="pl-c1">1615</span>         <span class="pl-k">if</span> <span class="pl-s1">mask</span>.<span class="pl-en">any</span>():
<span class="pl-c1">-&gt;</span> <span class="pl-c1">1616</span>             <span class="pl-k">raise</span> <span class="pl-v">ValueError</span>(<span class="pl-s">'labels %s not contained in axis'</span> <span class="pl-c1">%</span> <span class="pl-s1">labels</span>[<span class="pl-s1">mask</span>])
   <span class="pl-c1">1617</span>         <span class="pl-k">return</span> <span class="pl-s1">self</span>.<span class="pl-en">delete</span>(<span class="pl-s1">indexer</span>)
   <span class="pl-c1">1618</span>

<span class="pl-v">ValueError</span>: <span class="pl-s1">labels</span> [<span class="pl-s">'2000-01-03'</span>] <span class="pl-c1">not</span> <span class="pl-s1">contained</span> <span class="pl-c1">in</span> <span class="pl-s1">axis</span></pre></div>