From: oetiker Date: Fri, 1 Jun 2012 10:04:59 +0000 (+0000) Subject: rrd_graph_rpn: add a MEDIAN operator. -- Aaron Gallagher <_@habnab.it> X-Git-Url: https://git.verplant.org/?a=commitdiff_plain;h=8527e903bb76856a16e0f68f73ac11e4e087dfc3;p=rrdtool.git rrd_graph_rpn: add a MEDIAN operator. -- Aaron Gallagher <_@habnab.it> git-svn-id: svn://svn.oetiker.ch/rrdtool/trunk/program@2290 a5681a0c-68f1-0310-ab6d-d61299d08faa --- diff --git a/CONTRIBUTORS b/CONTRIBUTORS index 6c651eb..5b004df 100644 --- a/CONTRIBUTORS +++ b/CONTRIBUTORS @@ -9,6 +9,7 @@ Alex van den Bogaerdt (rrd_resize.c and more) Amos Shapira Andreas Kroomaa Andrew Turner (LAST consolidator) +Aaron Gallagher <_ with habnab.it> MEDIAN operator Benny Baumann 64bit stuff, --alt-autoscale-max Bernhard Fischer MMAP rewrite diff --git a/doc/rrdgraph_rpn.pod b/doc/rrdgraph_rpn.pod index 894fef1..87fc8e6 100644 --- a/doc/rrdgraph_rpn.pod +++ b/doc/rrdgraph_rpn.pod @@ -157,6 +157,16 @@ average, ignoring all UNKNOWN values in the process. Example: C +B + +pop one element (I) from the stack. Now pop I elements and find +the median, ignoring all UNKNOWN values in the process. If there are an even +number of non-UNKNOWN values, the average of the middle two will be pushed on +the stack. + +Example: C + + B Create a "sliding window" average of another data series. diff --git a/src/rrd_rpncalc.c b/src/rrd_rpncalc.c index 2bd1474..0677b30 100644 --- a/src/rrd_rpncalc.c +++ b/src/rrd_rpncalc.c @@ -387,6 +387,7 @@ rpnp_t *rpn_parse( match_op(OP_AVG, AVG) match_op(OP_ABS, ABS) match_op(OP_ADDNAN, ADDNAN) + match_op(OP_MEDIAN, MEDIAN) #undef match_op else if ((sscanf(expr, DEF_NAM_FMT "%n", vname, &pos) == 1) && ((rpnp[steps].ptr = (*lookup) (key_hash, vname)) != @@ -936,6 +937,51 @@ short rpn_calc( stackunderflow(0); rpnstack->s[stptr] = fabs(rpnstack->s[stptr]); break; + case OP_MEDIAN: + stackunderflow(0); + { + int elements = (int) rpnstack->s[stptr--]; + int final_elements = elements; + double *element_ptr = rpnstack->s + stptr - elements + 1; + double *goodvals = element_ptr; + double *badvals = element_ptr + elements - 1; + + stackunderflow(elements - 1); + + /* move values to consolidate the non-NANs for sorting, keeping + * track of how many NANs we encounter. */ + while (goodvals < badvals) { + if (isnan(*goodvals)) { + *goodvals = *badvals--; + --final_elements; + } else { + ++goodvals; + } + } + + stptr -= elements; + if (!final_elements) { + /* no non-NAN elements; push NAN */ + rpnstack->s[++stptr] = DNAN; + } else { + /* when goodvals and badvals meet, they might have met on a + * NAN, which wouldn't decrease final_elements. so, check + * that now. */ + if (isnan(*goodvals)) --final_elements; + /* and finally, take the median of the remaining non-NAN + * elements. */ + qsort(element_ptr, final_elements, sizeof(double), + rpn_compare_double); + if (final_elements % 2 == 1){ + rpnstack->s[++stptr] = element_ptr[ final_elements / 2 ]; + } + else { + rpnstack->s[++stptr] = 0.5 * ( element_ptr[ final_elements / 2 ] + element_ptr[ final_elements / 2 - 1 ] ); + } + } + } + break; + case OP_END: break; } diff --git a/src/rrd_rpncalc.h b/src/rrd_rpncalc.h index ab990b2..d27ff4c 100644 --- a/src/rrd_rpncalc.h +++ b/src/rrd_rpncalc.h @@ -19,7 +19,7 @@ enum op_en { OP_NUMBER = 0, OP_VARIABLE, OP_INF, OP_PREV, OP_NEGINF, OP_ATAN, OP_SQRT, OP_SORT, OP_REV, OP_TREND, OP_TRENDNAN, OP_ATAN2, OP_RAD2DEG, OP_DEG2RAD, OP_PREDICT,OP_PREDICTSIGMA, - OP_AVG, OP_ABS, OP_ADDNAN + OP_AVG, OP_ABS, OP_ADDNAN, OP_MEDIAN }; typedef struct rpnp_t {