New translations README (Chinese Simplified)

lang/zh/gklearn/gedlib/lib/libsvm.3.22/tools/README

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+This directory includes some useful codes:
+
+1. subset selection tools.
+2. parameter selection tools.
+3. LIBSVM format checking tools
+
+Part I: Subset selection tools
+
+Introduction
+============
+
+Training large data is time consuming. Sometimes one should work on a
+smaller subset first. The python script subset.py randomly selects a
+specified number of samples. For classification data, we provide a
+stratified selection to ensure the same class distribution in the
+subset.
+
+Usage: subset.py [options] dataset number [output1] [output2]
+
+This script selects a subset of the given data set.
+
+options:
+-s method : method of selection (default 0)
+     0 -- stratified selection (classification only)
+     1 -- random selection
+
+output1 : the subset (optional)
+output2 : the rest of data (optional)
+
+If output1 is omitted, the subset will be printed on the screen.
+
+Example
+=======
+
+> python subset.py heart_scale 100 file1 file2
+
+From heart_scale 100 samples are randomly selected and stored in
+file1. All remaining instances are stored in file2.
+
+
+Part II: Parameter Selection Tools
+
+Introduction
+============
+
+grid.py is a parameter selection tool for C-SVM classification using
+the RBF (radial basis function) kernel. It uses cross validation (CV)
+technique to estimate the accuracy of each parameter combination in
+the specified range and helps you to decide the best parameters for
+your problem.
+
+grid.py directly executes libsvm binaries (so no python binding is needed)
+for cross validation and then draw contour of CV accuracy using gnuplot.
+You must have libsvm and gnuplot installed before using it. The package
+gnuplot is available at http://www.gnuplot.info/
+
+On Mac OSX, the precompiled gnuplot file needs the library Aquarterm,
+which thus must be installed as well. In addition, this version of
+gnuplot does not support png, so you need to change "set term png
+transparent small" and use other image formats. For example, you may
+have "set term pbm small color".
+
+Usage: grid.py [grid_options] [svm_options] dataset
+
+grid_options :
+-log2c {begin,end,step | "null"} : set the range of c (default -5,15,2)
+    begin,end,step -- c_range = 2^{begin,...,begin+k*step,...,end}
+    "null"         -- do not grid with c
+-log2g {begin,end,step | "null"} : set the range of g (default 3,-15,-2)
+    begin,end,step -- g_range = 2^{begin,...,begin+k*step,...,end}
+    "null"         -- do not grid with g
+-v n : n-fold cross validation (default 5)
+-svmtrain pathname : set svm executable path and name
+-gnuplot {pathname | "null"} :
+    pathname -- set gnuplot executable path and name
+    "null"   -- do not plot 
+-out {pathname | "null"} : (default dataset.out)
+    pathname -- set output file path and name
+    "null"   -- do not output file
+-png pathname : set graphic output file path and name (default dataset.png)
+-resume [pathname] : resume the grid task using an existing output file (default pathname is dataset.out)
+    Use this option only if some parameters have been checked for the SAME data.
+
+svm_options : additional options for svm-train
+
+The program conducts v-fold cross validation using parameter C (and gamma)
+= 2^begin, 2^(begin+step), ..., 2^end.
+
+You can specify where the libsvm executable and gnuplot are using the
+-svmtrain and -gnuplot parameters.
+
+For windows users, please use pgnuplot.exe. If you are using gnuplot
+3.7.1, please upgrade to version 3.7.3 or higher. The version 3.7.1
+has a bug. If you use cygwin on windows, please use gunplot-x11.
+
+If the task is terminated accidentally or you would like to change the
+range of parameters, you can apply '-resume' to save time by re-using
+previous results.  You may specify the output file of a previous run
+or use the default (i.e., dataset.out) without giving a name. Please
+note that the same condition must be used in two runs. For example,
+you cannot use '-v 10' earlier and resume the task with '-v 5'.
+
+The value of some options can be "null." For example, `-log2c -1,0,1
+-log2 "null"' means that C=2^-1,2^0,2^1 and g=LIBSVM's default gamma
+value. That is, you do not conduct parameter selection on gamma.
+
+Example
+=======
+
+> python grid.py -log2c -5,5,1 -log2g -4,0,1 -v 5 -m 300 heart_scale
+
+Users (in particular MS Windows users) may need to specify the path of
+executable files. You can either change paths in the beginning of
+grid.py or specify them in the command line. For example,
+
+> grid.py -log2c -5,5,1 -svmtrain "c:\Program Files\libsvm\windows\svm-train.exe" -gnuplot c:\tmp\gnuplot\binary\pgnuplot.exe -v 10 heart_scale
+
+Output: two files
+dataset.png: the CV accuracy contour plot generated by gnuplot
+dataset.out: the CV accuracy at each (log2(C),log2(gamma))
+
+The following example saves running time by loading the output file of a previous run.
+
+> python grid.py -log2c -7,7,1 -log2g -5,2,1 -v 5 -resume heart_scale.out heart_scale
+
+Parallel grid search
+====================
+
+You can conduct a parallel grid search by dispatching jobs to a
+cluster of computers which share the same file system. First, you add
+machine names in grid.py:
+
+ssh_workers = ["linux1", "linux5", "linux5"]
+
+and then setup your ssh so that the authentication works without
+asking a password.
+
+The same machine (e.g., linux5 here) can be listed more than once if
+it has multiple CPUs or has more RAM. If the local machine is the
+best, you can also enlarge the nr_local_worker. For example:
+
+nr_local_worker = 2
+
+Example:
+
+> python grid.py heart_scale
+[local] -1 -1 78.8889  (best c=0.5, g=0.5, rate=78.8889)
+[linux5] -1 -7 83.3333  (best c=0.5, g=0.0078125, rate=83.3333)
+[linux5] 5 -1 77.037  (best c=0.5, g=0.0078125, rate=83.3333)
+[linux1] 5 -7 83.3333  (best c=0.5, g=0.0078125, rate=83.3333)
+.
+.
+.
+
+If -log2c, -log2g, or -v is not specified, default values are used.
+
+If your system uses telnet instead of ssh, you list the computer names
+in telnet_workers.
+
+Calling grid in Python
+======================
+
+In addition to using grid.py as a command-line tool, you can use it as a
+Python module. 
+
+>>> rate, param = find_parameters(dataset, options)
+
+You need to specify `dataset' and `options' (default ''). See the following example.
+
+> python
+
+>>> from grid import *
+>>> rate, param = find_parameters('../heart_scale', '-log2c -1,1,1 -log2g -1,1,1')
+[local] 0.0 0.0 rate=74.8148 (best c=1.0, g=1.0, rate=74.8148)
+[local] 0.0 -1.0 rate=77.037 (best c=1.0, g=0.5, rate=77.037)
+.
+.
+[local] -1.0 -1.0 rate=78.8889 (best c=0.5, g=0.5, rate=78.8889)
+.
+.
+>>> rate
+78.8889
+>>> param
+{'c': 0.5, 'g': 0.5}
+
+
+Part III: LIBSVM format checking tools
+
+Introduction
+============
+
+`svm-train' conducts only a simple check of the input data. To do a
+detailed check, we provide a python script `checkdata.py.'
+
+Usage: checkdata.py dataset
+
+Exit status (returned value): 1 if there are errors, 0 otherwise.
+
+This tool is written by Rong-En Fan at National Taiwan University.
+
+Example
+=======
+
+> cat bad_data
+1 3:1 2:4
+> python checkdata.py bad_data
+line 1: feature indices must be in an ascending order, previous/current features 3:1 2:4
+Found 1 lines with error.
+
+