diff options
Diffstat (limited to 'web/api/queries/stddev/stddev.h')
-rw-r--r-- | web/api/queries/stddev/stddev.h | 120 |
1 files changed, 0 insertions, 120 deletions
diff --git a/web/api/queries/stddev/stddev.h b/web/api/queries/stddev/stddev.h deleted file mode 100644 index f7a1a06c..00000000 --- a/web/api/queries/stddev/stddev.h +++ /dev/null @@ -1,120 +0,0 @@ -// SPDX-License-Identifier: GPL-3.0-or-later - -#ifndef NETDATA_API_QUERIES_STDDEV_H -#define NETDATA_API_QUERIES_STDDEV_H - -#include "../query.h" -#include "../rrdr.h" - -// this implementation comes from: -// https://www.johndcook.com/blog/standard_deviation/ - -struct tg_stddev { - long count; - NETDATA_DOUBLE m_oldM, m_newM, m_oldS, m_newS; -}; - -static inline void tg_stddev_create(RRDR *r, const char *options __maybe_unused) { - r->time_grouping.data = onewayalloc_callocz(r->internal.owa, 1, sizeof(struct tg_stddev)); -} - -// resets when switches dimensions -// so, clear everything to restart -static inline void tg_stddev_reset(RRDR *r) { - struct tg_stddev *g = (struct tg_stddev *)r->time_grouping.data; - g->count = 0; -} - -static inline void tg_stddev_free(RRDR *r) { - onewayalloc_freez(r->internal.owa, r->time_grouping.data); - r->time_grouping.data = NULL; -} - -static inline void tg_stddev_add(RRDR *r, NETDATA_DOUBLE value) { - struct tg_stddev *g = (struct tg_stddev *)r->time_grouping.data; - - g->count++; - - // See Knuth TAOCP vol 2, 3rd edition, page 232 - if (g->count == 1) { - g->m_oldM = g->m_newM = value; - g->m_oldS = 0.0; - } - else { - g->m_newM = g->m_oldM + (value - g->m_oldM) / g->count; - g->m_newS = g->m_oldS + (value - g->m_oldM) * (value - g->m_newM); - - // set up for next iteration - g->m_oldM = g->m_newM; - g->m_oldS = g->m_newS; - } -} - -static inline NETDATA_DOUBLE tg_stddev_mean(struct tg_stddev *g) { - return (g->count > 0) ? g->m_newM : 0.0; -} - -static inline NETDATA_DOUBLE tg_stddev_variance(struct tg_stddev *g) { - return ( (g->count > 1) ? g->m_newS/(NETDATA_DOUBLE)(g->count - 1) : 0.0 ); -} -static inline NETDATA_DOUBLE tg_stddev_stddev(struct tg_stddev *g) { - return sqrtndd(tg_stddev_variance(g)); -} - -static inline NETDATA_DOUBLE tg_stddev_flush(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr) { - struct tg_stddev *g = (struct tg_stddev *)r->time_grouping.data; - - NETDATA_DOUBLE value; - - if(likely(g->count > 1)) { - value = tg_stddev_stddev(g); - - if(!netdata_double_isnumber(value)) { - value = 0.0; - *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY; - } - } - else if(g->count == 1) { - value = 0.0; - } - else { - value = 0.0; - *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY; - } - - tg_stddev_reset(r); - - return value; -} - -// https://en.wikipedia.org/wiki/Coefficient_of_variation -static inline NETDATA_DOUBLE tg_stddev_coefficient_of_variation_flush(RRDR *r, RRDR_VALUE_FLAGS *rrdr_value_options_ptr) { - struct tg_stddev *g = (struct tg_stddev *)r->time_grouping.data; - - NETDATA_DOUBLE value; - - if(likely(g->count > 1)) { - NETDATA_DOUBLE m = tg_stddev_mean(g); - value = 100.0 * tg_stddev_stddev(g) / ((m < 0)? -m : m); - - if(unlikely(!netdata_double_isnumber(value))) { - value = 0.0; - *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY; - } - } - else if(g->count == 1) { - // one value collected - value = 0.0; - } - else { - // no values collected - value = 0.0; - *rrdr_value_options_ptr |= RRDR_VALUE_EMPTY; - } - - tg_stddev_reset(r); - - return value; -} - -#endif //NETDATA_API_QUERIES_STDDEV_H |