C4.5算法学习【一】

为了记录，也为了日后重温，更为了交学习报告，决定写下每天的学习情况

先贴点学习资料网站什么的：

http://www2.cs.uregina.ca/~dbd/cs831/index.html（刚好有weka，kdd的介绍，更刚好又C4.5）

 

"Quinlan" "C4. 5: programs for machine learning"的电子版，可惜不能下

http://www.google.com/books?hl=zh-CN&lr=&id=HExncpjbYroC&oi=fnd&pg=PR7&dq=%22Quinlan%22+%22C4.+5:+programs+for+machine+learning%22+&ots=nJpdcSx0Xo&sig=djBDwgiSRoqHinBnnMzxJo3vOpk#v=onepage&q=&f=false

 

关于C4.5的介绍暂时略。

本来想看weka的源码的，可以根本就是白费工，Java才刚学，杯具.....

第一天分析：

结合这个网页的资料：

http://www2.cs.uregina.ca/~dbd/cs831/notes/ml/dtrees/c4.5/tutorial.html

下载里面的源码：c4.5r8.tar.gz

 

 

因为是"C4.5 Release 8 Installation Instructions for UNIX"

所以只好弄到我的虚拟机里的linux（ubuntu）里了。

 

然后按照这个：

1. Download the C4.5 source code.
2. Decompress the archive:
3. Type "tar xvzf c4.5r8.tar" (not universally supported), or, alternatively,
4. Type "gunzip c4.5r8.tar.gz" to decompress the gzip archive, and then
   Type "tar xvf c4.5r8.tar" to decompress the tar archive.
5. Change to ./R8/Src
6. Type "make all" to compile the executables.
7. Put the executables into a "bin" subdirectory and include it in the path for command-line usage.

弄好就可以用了。

 

源码就在 R8/Src里

 

先从 c4.5.c  这个文件开始吧。看着代码才发现自己的C/C++水平很菜！分析的不对请指出。

 

 

 

 #include "defns.i" #include "types.i" //#include "extern.i" /* External data, described in extern.i */ short MaxAtt, /* max att number *///最大属性数目 MaxClass, /* max class number *///最大类数 MaxDiscrVal = 2;/* max discrete values for any att */ ItemNo MaxItem; /* max data item number */ Description *Item; /* data items */ /* typedef union _attribute_value { DiscrValue _discr_val; float _cont_val; } AttValue, *Description; */ DiscrValue *MaxAttVal; /* number of values for each att */ //short char *SpecialStatus; /* special att treatment */ String *ClassName, /* class names *///类名 *AttName, /* att names *///属性名 **AttValName, /* att value names *///属性的值的名 FileName = "DF"; /* family name of files */ short VERBOSITY = 0, /* verbosity level (0 = none) *///冗长级别？ TRIALS = 10; /* number of trees to be grown */ //char //typedef char Boolean, *String, *Set; Boolean GAINRATIO = true, /* true=gain ratio, false=gain *///true表示信息增益率,false表示信息增益 SUBSET = false, /* true if subset tests allowed */ BATCH = true, /* true if windowing turned off */ UNSEENS = false, /* true if to evaluate on test data */ PROBTHRESH = false; /* true if to use soft thresholds */ ItemNo MINOBJS = 2, /* minimum items each side of a cut */ WINDOW = 0, /* initial window size */ INCREMENT = 0; /* max window increment each iteration */ float CF = 0.25; /* confidence limit for tree pruning *///置信界限？ Tree *Pruned; Boolean AllKnown = true; /* true if there have been no splits on atts with missing values above the current position in the tree */ main(Argc, Argv) /* ---- */ int Argc; char *Argv[]; { int o; extern char *optarg; //#include<unistd.h>里有(在getopt.c也有 extern int optind; //#include<unistd.h>里有(在getopt.c也有 /* extern的用法？？？？？？？不会啊，杯具！ */ Boolean FirstTime=true; short Best, BestTree(); PrintHeader("decision tree generator"); /* Process options */ //处理选项及其参数。 //unistd.h 函数说明 getopt()用来分析命令行参数 //百度了一翻 - -！ while ( (o = getopt(Argc, Argv, "f:bupv:t:w:i:gsm:c:")) != EOF ) { if ( FirstTime ) { printf("/n Options:/n"); FirstTime = false; } switch (o) { case 'f': FileName = optarg; printf("/tFile stem

 

杯具一次插不完 - -！ 略掉一部分不是很重要的继续插 - -！

/* Initialise */ //读入类名，属性名，属性值？统计实例数、属性数？ //数据存放于？下面的说明？ /*************************************************************************/ /* */ /* Read the names of classes, attributes and legal attribute values. */ /* On completion, these names are stored in: */ /* ClassName - class names *///放类名? /* AttName - attribute names *///放属性名? /* AttValName - attribute value names *///属性值? /* with: */ /* MaxAttVal - number of values for each attribute */ /* */ /* Other global variables set are: */ /* MaxAtt - maximum attribute number */ /* MaxClass - maximum class number */ /* MaxDiscrVal - maximum discrete values for any attribute */ /* */ /* Note: until the number of attributes is known, the name */ /* information is assembled in local arrays */ /* */ /*************************************************************************/ GetNames(); //golf.names 在getnames.c GetData(".data"); //golf.data 在getdata.c printf("/nRead %d cases (%d attributes) from %s.data/n", MaxItem+1, MaxAtt+1, FileName); //14 4 golf /* Build decision trees *///建立决策树 if ( BATCH ) { TRIALS = 1; OneTree(); //where? Best = 0; } else { Best = BestTree(); //where? } /* Soften thresholds in best tree */ if ( PROBTHRESH ) { printf("Softening thresholds"); if ( ! BATCH ) printf(" for best tree from trial %d", Best); printf("/n"); SoftenThresh(Pruned[Best]); printf("/n"); PrintTree(Pruned[Best]); } /* Save best tree */ if ( BATCH || TRIALS == 1 ) { printf("/nTree saved/n"); } else { printf("/nBest tree from trial %d saved/n", Best); } SaveTree(Pruned[Best], ".tree"); /* Evaluation */ printf("/n/nEvaluation on training data (%d items):/n", MaxItem+1); Evaluate(false, Best); if ( UNSEENS ) { GetData(".test"); printf("/nEvaluation on test data (%d items):/n", MaxItem+1); Evaluate(true, Best); } exit(0); }