/*?SCCS?@（#）anova.c?1.8?08/13/01??*/
/*
**?The?four?routines?for?anova?splitting
*/
#include?
#include?“rpart.h“
#include?“rpartS.h“
#include?“node.h“
#include?“rpartproto.h“

static?double?*mean?*sums;
static?double?*wts;
static?int?*countn;
static?int?*tsplit;

int?anovainit（int?n????????double?*y[]??int?maxcat?char?**error?
??????????double?*parm?int?*size????int?who????double?*wt）
????{
????if?（who==1?&&?maxcat?>0）?{
????graycode_init0（maxcat）;
????countn??=?（int?*）ALLOC（2*maxcat?sizeof（int））;
????tsplit??=?countn?+?maxcat;
????mean???=?（double?*）ALLOC（3*maxcat?sizeof（double））;
????wts????=?mean?+?maxcat;
????sums???=?wts?+?maxcat;
????}
????*size?=?1;
????return（0）;
????}
/*
**?The?anova?evaluation?function.??Return?the?mean?and?the?ss.
*/
void?anovass（int?n?double?*y[]?double?*value?double?*risk
?????????double?*wt）?{
????int?i;
????double?temp?twt;
????double?mean?ss;

????temp?=?0;
????twt??=?0;????????/*?sum?of?the?weights?*/
????for?（i=0;?i????temp?+=?*y[i]?*?wt[i];
????twt??+=?wt[i];
????}
????mean?=?temp/twt;

????ss?=0;
????for?（i=0;?i????temp?=?*y[i]?-?mean;
????if?（rp.dissim==1）?ss?+=?temp?*?temp?*?wt[i];
????else?if?（rp.dissim==2）?ss?+=?fabs（temp）?*?wt[i];
????}

????*value?=?mean;
????*risk?=?ss;
????}

/*
**?The?anova?splitting?function.??Find?that?split?point?in?x?such?that
**??the?sum?of?squares?of?y?within?the?two?groups?is?decreased?as?much
**??as?possible.??It?is?not?necessary?to?actually?calculate?the?SS?the
**??improvement?involves?only?means?in?the?two?groups.
*/
void?anova（int?n????double?*y[]?????FLOAT?*x?????int?nclass?
???????int?edge?double?*improve?FLOAT?*split?int?*csplit?
???????double?myrisk?????????????double?*wt）
????{
????int?ij;
????double?temp?=?0;
????double?left_sum?right_sum;
????double?left_wt?right_wt;
????int????left_n??right_n;
????double?grandmean?best;
????int?direction?=?LEFT;
????int?where?=?0;

????/*
????**?The?improvement?of?a?node?is?SS?-?（SS_L?+?SS_R）?where
????**???SS?=?sum?of?squares?in?a?node?=?\sum?w_i?（x_i?-?\bar?x）^2?where
????**?of?course?\bar?x?is?a?weighted?mean?\sum?w_i?x_i?/?\sum?w_i
????**?Using?the?identity?
????**????\sum?w_i（x_?-?\bar?x）^2?=?\sum?w_i?（x_i-c）^2?-?（\sum?w_i）（c-\bar?x）^2
????**?the?improvement?=?w_l*（left?mean?-?grand?mean）^2?
????**??????????????????+w_r*（right?mean-?grand?mean）^2
????**?where?w_l?is?the?sum?of?weights?in?the?left?node?w_r?similarly.?
????*/
????right_wt?=0;
????right_n??=?n;
????right_sum?=0;
????for?（i=0;?i????right_sum?+=?*y[i]?*?wt[i];
????right_wt??+=?wt[i];
????}
????grandmean?=?right_sum/right_wt;

????if?（nclass==0）?{???/*?continuous?predictor?*/
????????left_sum=0;???/*?No?data?in?left?branch?to?start?*/
????left_wt?=0;???left_n?=0;
????right_sum=0;??/*after?subracting?grand?mean?it‘s?zero?*/
????best????=?0;
????for?（i=0;?right_n>edge;?i++）?{
????????left_wt?+=?wt[i];??
????????right_wt?-=?wt[i];
????????left_n++;
????????right_n--;
????????temp?=?（*y[i]?-?gr