1
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN""http://www.w3.org/TR/html4/loose.dtd">
5
>Selecting an User Entry Point (UEP) in your
9
CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
11
TITLE="PyTables User's Guide"
12
HREF="index.html"><LINK
14
TITLE="Optimization tips"
15
HREF="c5270.html"><LINK
17
TITLE="Getting the most from the node LRU cache"
18
HREF="x5576.html"><LINK
20
TITLE="Compacting your PyTables
23
HREF="x5689.html"></HEAD
34
SUMMARY="Header navigation table"
46
> User's Guide: Hierarchical datasets in Python - Release 1.3.2</TH
62
>Chapter 5. Optimization tips</TD
83
>5.7. Selecting an User Entry Point (UEP) in your
93
> After the introduction
94
of the new object tree cache in PyTables 1.2, this feature
95
is not very useful anymore and might become
102
> in future versions.
112
your data file with many nodes on it, creating the object
113
tree would take long time. Many times, however, you are
114
interested only in access to a part of the complete tree, so
115
you won't strictly need PyTables to build the entire object
116
tree in-memory, but only the <SPAN
125
>This is where the <SAMP
126
CLASS="computeroutput"
130
CLASS="computeroutput"
133
HREF="c1381.html#openFileDescr"
135
>) can be helpful. Imagine that
136
you have a file called <SAMP
137
CLASS="computeroutput"
140
associated tree that you can see in figure <A
141
HREF="x5654.html#rootUEPfig1"
143
>, and you are interested only in
144
the section marked in red. You can avoid the build of all
145
the object tree by saying to <SAMP
146
CLASS="computeroutput"
149
root will be the <SAMP
150
CLASS="computeroutput"
151
>/Group2/Group3</SAMP
156
> fileh = openFile("test.h5", rootUEP="/Group2/Group3")
159
>As a result, the actual object tree built will be like the
160
one that can be seen in <A
161
HREF="x5654.html#rootUEPfig2"
166
>Of course this has been a simple example and the use
168
CLASS="computeroutput"
170
> parameter was not very
171
necessary. But when you have <SPAN
178
a tree, you will certainly appreciate the
180
CLASS="computeroutput"
191
>Figure 5.17. Complete tree in file <SPAN
194
>, and subtree of interest for
202
SRC="rootUEP1.png"></P
212
>Figure 5.18. Resulting object tree derived from the use of the
223
SRC="rootUEP2.png"></P
232
SUMMARY="Footer navigation table"
271
>Getting the most from the node LRU cache</TD
285
>Compacting your <SPAN
b'\\ No newline at end of file'