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    Hi yt users,<br>
    <br>
    I'm having a problem generating streamlines. I'm following the
    cookbook script and it works fine for the IsolatedGalaxy dataset,
    but not for my own data (also Enzo). The error I'm getting is the
    following:<br>
    <br>
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      <pre style="padding: 0px; font-family: monospace; font-size: 14.3000001907349px; color: rgb(0, 0, 0); border-radius: 0px; display: block; margin: 0px; line-height: 17.6033000946045px; word-break: break-all; word-wrap: break-word; white-space: pre-wrap; border: 0px; vertical-align: baseline; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: left; text-indent: 0px; text-transform: none; widows: 1; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255);"><span class="ansired" style="color: rgb(139, 0, 0);">---------------------------------------------------------------------------</span>
<span class="ansired" style="color: rgb(139, 0, 0);">AttributeError</span>                            Traceback (most recent call last)
<span class="ansigreen" style="color: rgb(0, 100, 0);"><ipython-input-20-d3a0fa7307d4></span> in <span class="ansicyan" style="color: rgb(70, 130, 180);"><module><span class="ansiblue" style="color: rgb(0, 0, 139);">()</span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">      5</span> </span>pos <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> c<span class="ansiyellow" style="color: rgb(165, 42, 42);">+</span>pos_dx<span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">      6</span> <span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">----> 7<span class="ansiyellow" style="color: rgb(165, 42, 42);"> </span>streamlines</span> <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> Streamlines<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>pf<span class="ansiyellow" style="color: rgb(165, 42, 42);">,</span>pos<span class="ansiyellow" style="color: rgb(165, 42, 42);">,</span><span class="ansiblue" style="color: rgb(0, 0, 139);">'x-velocity'</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">,</span> <span class="ansiblue" style="color: rgb(0, 0, 139);">'y-velocity'</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">,</span> <span class="ansiblue" style="color: rgb(0, 0, 139);">'z-velocity'</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">,</span> length<span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span><span class="ansicyan" style="color: rgb(70, 130, 180);">1.0</span>
 <span cla
ss="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">      8</span> <span class="ansired" style="color: rgb(139, 0, 0);">#streamlines = Streamlines(pf,pos,'x-velocity', 'y-velocity', 'z-velocity', length=pf.domain_width[0])</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">      9</span> streamlines<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>integrate_through_volume<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>

<span class="ansigreen" style="color: rgb(0, 100, 0);">/data/users/borm/YT/yt-x86_64/src/yt-hg/yt/visualization/streamlines.pyc</span> in <span class="ansicyan" style="color: rgb(70, 130, 180);">__init__<span class="ansiblue" style="color: rgb(0, 0, 139);">(self, pf, positions, xfield, yfield, zfield, volume, dx, length, direction, get_magnitude)</span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    102</span>             volume = AMRKDTree(self.pf, fields=[self.xfield,self.yfield,self.zfield],
<span class="ansigreen" style="color: rgb(0, 100, 0);">    103</span>                             log_fields=[False,False,False])
<span class="ansigreen" style="color: rgb(0, 100, 0);">--> 104<span class="ansiyellow" style="color: rgb(165, 42, 42);">             </span>volume</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span></span>join_parallel_trees<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    105</span>         self<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>volume <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> volume<span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    106</span>         <span class="ansigreen" style="color: rgb(0, 100, 0);">if</span> dx <span class="ansigreen" style="color: rgb(0, 100, 0);">is</span> None<span class="ansiyellow" style="color: rgb(165, 42, 42);">:</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>

<span class="ansigreen" style="color: rgb(0, 100, 0);">/data/users/borm/YT/yt-x86_64/src/yt-hg/yt/utilities/amr_kdtree/amr_kdtree.pyc</span> in <span class="ansicyan" style="color: rgb(70, 130, 180);">join_parallel_trees<span class="ansiblue" style="color: rgb(0, 0, 139);">(self)</span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    456</span>         </span>nid <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> np<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>array<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>nid<span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    457</span>         new_tree = self.rebuild_tree_from_array(nid, pid, lid, 
<span class="ansigreen" style="color: rgb(0, 100, 0);">--> 458<span class="ansiyellow" style="color: rgb(165, 42, 42);">             rid, les, res, gid, splitdims, splitposs)
</span><span class="ansigreen" style="color: rgb(0, 100, 0);">    459</span> <span class="ansiyellow" style="color: rgb(165, 42, 42);"></span></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    460</span>     <span class="ansigreen" style="color: rgb(0, 100, 0);">def</span> get_node_arrays<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>self<span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">:</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>

<span class="ansigreen" style="color: rgb(0, 100, 0);">/data/users/borm/YT/yt-x86_64/src/yt-hg/yt/utilities/amr_kdtree/amr_kdtree.pyc</span> in <span class="ansicyan" style="color: rgb(70, 130, 180);">rebuild_tree_from_array<span class="ansiblue" style="color: rgb(0, 0, 139);">(self, nids, pids, lids, rids, les, res, gids, splitdims, splitposs)</span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    505</span>         </span>N <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> nids<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>shape<span class="ansiyellow" style="color: rgb(165, 42, 42);">[</span><span class="ansicyan" style="color: rgb(70, 130, 180);">0</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">]</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    506</span>         <span class="ansigreen" style="color: rgb(0, 100, 0);">for</span> i <span class="ansigreen" style="color: rgb(0, 100, 0);">in</span> xrange<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>N<span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">:</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">--> 507<span class="ansiyellow" style="color: rgb(165, 42, 42);">             </span>n</span> <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> self<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>get_node<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>nids<span class="ansiyellow" style="color: rgb(165, 42, 42);">[</span>i<span class="ansiyellow" style="color: rgb(165, 42, 42);">]</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    508</span>             n<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>set_left_edge<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>les<span class="ansiyellow" style="color: rgb(165, 42, 42);">[</span>i<span class="ansiyellow" style="color: rgb(165, 42, 42);">]</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    509</span>             n<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>set_right_edge<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>res<span class="ansiyellow" style="color: rgb(165, 42, 42);">[</span>i<span class="ansiyellow" style="color: rgb(165, 42, 42);">]</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>

<span class="ansigreen" style="color: rgb(0, 100, 0);">/data/users/borm/YT/yt-x86_64/src/yt-hg/yt/utilities/amr_kdtree/amr_kdtree.pyc</span> in <span class="ansicyan" style="color: rgb(70, 130, 180);">get_node<span class="ansiblue" style="color: rgb(0, 0, 139);">(self, nodeid)</span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    212</span>         <span class="ansigreen" style="color: rgb(0, 100, 0);">for</span> </span>depth <span class="ansigreen" style="color: rgb(0, 100, 0);">in</span> range<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span><span class="ansicyan" style="color: rgb(70, 130, 180);">1</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">,</span>len<span class="ansiyellow" style="color: rgb(165, 42, 42);">(</span>path<span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">)</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">:</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    213</span>             <span class="ansigreen" style="color: rgb(0, 100, 0);">if</span> path<span class="ansiyellow" style="color: rgb(165, 42, 42);">[</span>depth<span class="ansiyellow" style="color: rgb(165, 42, 42);">]</span> <span class="ansiyellow" style="color: rgb(165, 42, 42);">==</span> <span class="ansiblue" style="color: rgb(0, 0, 139);">'0'</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">:</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">--> 214<span class="ansiyellow" style="color: rgb(165, 42, 42);">                 </span>temp</span> <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> temp<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>left<span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    215</span>             <span class="ansigreen" style="color: rgb(0, 100, 0);">else</span><span class="ansiyellow" style="color: rgb(165, 42, 42);">:</span><span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>
<span class="ansigreen" style="color: rgb(0, 100, 0);">    216</span>                 temp <span class="ansiyellow" style="color: rgb(165, 42, 42);">=</span> temp<span class="ansiyellow" style="color: rgb(165, 42, 42);">.</span>right<span class="ansiyellow" style="color: rgb(165, 42, 42);"></span>

<span class="ansired" style="color: rgb(139, 0, 0);">AttributeError</span>: 'NoneType' object has no attribute 'left'
</pre>
    </blockquote>
    Though sometimes with a different dataset I also get <br>
    <blockquote>
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      <pre style="padding: 0px; font-family: monospace; font-size: 14.3000001907349px; color: rgb(0, 0, 0); border-radius: 0px; display: block; margin: 0px; line-height: 17.6033000946045px; word-break: break-all; word-wrap: break-word; white-space: pre-wrap; border: 0px; vertical-align: baseline; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: left; text-indent: 0px; text-transform: none; widows: 1; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255);"><span class="ansired" style="color: rgb(139, 0, 0);">AttributeError</span>: 'NoneType' object has no attribute 'right'
</pre>
    </blockquote>
    I'm using yt 2.6, but I've also tried with yt 3.1 and I get the same
    error there (only it takes much, much longer before it crashes?) My
    datasets do not have particles, not sure if that may be relevant.<br>
    <br>
    Any help is much appreciated!<br>
    <br>
    Cheers,<br>
    Caroline<br>
    <pre style="padding: 0px; font-family: monospace; font-size: 14.3000001907349px; color: rgb(0, 0, 0); border-radius: 0px; display: block; margin: 0px; line-height: 17.6033000946045px; word-break: break-all; word-wrap: break-word; white-space: pre-wrap; border: 0px; vertical-align: baseline; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: left; text-indent: 0px; text-transform: none; widows: 1; word-spacing: 0px; -webkit-text-stroke-width: 0px; background-color: rgb(255, 255, 255);">
</pre>
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