原理:就是说划一个时间段,在这个时间段里面找到一个 最低峰值 ,然后确定一个 周期 ，然后分别在 这个峰值 前间隔 0.5个周期 的 1周期里 和 这个峰值 后间隔 0.5个周期 的 1周期 里找到一个最低峰值。 然后根据这几个值来确定瞬时心率。
- (void)analysisPointsWith:(NSDictionary *)point {
[self.points addObject:point];
if (self.points.count<=30) return;
int count = (int)self.points.count;
if (self.points.count%10 == 0) {
int d_i_c = 0; //最低峰值的位置 姑且算在中间位置 c->center
int d_i_l = 0; //最低峰值左面的最低峰值位置 l->left
int d_i_r = 0; //最低峰值右面的最低峰值位置 r->right
float trough_c = 0; //最低峰值的浮点值
float trough_l = 0; //最低峰值左面的最低峰值浮点值
float trough_r = 0; //最低峰值右面的最低峰值浮点值
// 1.先确定数据中的最低峰值
for (int i = 0; i < count; i++) {
float trough = [[[self.points[i] allObjects] firstObject] floatValue];
if (trough < trough_c) {
trough_c = trough;
d_i_c = i;
}
}
// 2.找到最低峰值以后 以最低峰值为中心 找到前0.5-1.5周期中的最低峰值 和后0.5-1.5周期的最低峰值
if (d_i_c >= 1.5*T) {
// a.如果最低峰值处在中心位置， 即距离前后都至少有1.5个周期
if (d_i_c <= count-1.5*T) {
// 左面最低峰值
for (int j = d_i_c - 0.5*T; j > d_i_c - 1.5*T; j--) {
float trough = [[[self.points[j] allObjects] firstObject] floatValue];
if (trough < trough_l) {
trough_l = trough;
d_i_l = j;
}
}
// 右面最低峰值
for (int k = d_i_c + 0.5*T; k < d_i_c + 1.5*T; k++) {
float trough = [[[self.points[k] allObjects] firstObject] floatValue];
if (trough < trough_r) {
trough_r = trough;
d_i_r = k;
}
}
}
// b.如果最低峰值右面不够1.5个周期 分两种情况 不够0.5个周期和够0.5个周期
else {
// b.1 够0.5个周期
if (d_i_c <count-0.5*T) {
// 左面最低峰值
for (int j = d_i_c - 0.5*T; j > d_i_c - 1.5*T; j--) {
float trough = [[[self.points[j] allObjects] firstObject] floatValue];
if (trough < trough_l) {
trough_l = trough;
d_i_l = j;
}
}
// 右面最低峰值
for (int k = d_i_c + 0.5*T; k < count; k++) {
float trough = [[[self.points[k] allObjects] firstObject] floatValue];
if (trough < trough_r) {
trough_r = trough;
d_i_r = k;
}
}
}
// b.2 不够0.5个周期
else {
// 左面最低峰值
for (int j = d_i_c - 0.5*T; j > d_i_c - 1.5*T; j--) {
float trough = [[[self.points[j] allObjects] firstObject] floatValue];
if (trough < trough_l) {
trough_l = trough;
d_i_l = j;
}
}
}
}
}
// c. 如果左面不够1.5个周期 一样分两种情况 够0.5个周期 不够0.5个周期
else {
// c.1 够0.5个周期
if (d_i_c>0.5*T) {
// 左面最低峰值
for (int j = d_i_c - 0.5*T; j > 0; j--) {
float trough = [[[self.points[j] allObjects] firstObject] floatValue];
if (trough < trough_l) {
trough_l = trough;
d_i_l = j;
}
}
// 右面最低峰值
for (int k = d_i_c + 0.5*T; k < d_i_c + 1.5*T; k++) {
float trough = [[[self.points[k] allObjects] firstObject] floatValue];
if (trough < trough_r) {
trough_r = trough;
d_i_r = k;
}
}
}
// c.2 不够0.5个周期
else {
// 右面最低峰值
for (int k = d_i_c + 0.5*T; k < d_i_c + 1.5*T; k++) {
float trough = [[[self.points[k] allObjects] firstObject] floatValue];
if (trough < trough_r) {
trough_r = trough;
d_i_r = k;
}
}
}
}
// 3. 确定哪一个与最低峰值更接近 用最接近的一个最低峰值测出瞬时心率 60*1000两个峰值的时间差
if (trough_l-trough_c < trough_r-trough_c) {
NSDictionary *point_c = self.points[d_i_c];
NSDictionary *point_l = self.points[d_i_l];
double t_c = [[[point_c allKeys] firstObject] doubleValue];
double t_l = [[[point_l allKeys] firstObject] doubleValue];
NSInteger fre = (NSInteger)(60*1000)/(t_c - t_l);
if (self.frequency)
self.frequency(fre);
if ([self.delegate respondsToSelector:@selector(startHeartDelegateRateFrequency:)])
[self.delegate startHeartDelegateRateFrequency:fre];
} else {
NSDictionary *point_c = self.points[d_i_c];
NSDictionary *point_r = self.points[d_i_r];
double t_c = [[[point_c allKeys] firstObject] doubleValue];
double t_r = [[[point_r allKeys] firstObject] doubleValue];
NSInteger fre = (NSInteger)(60*1000)/(t_r - t_c);
if (self.frequency)
self.frequency(fre);
if ([self.delegate respondsToSelector:@selector(startHeartDelegateRateFrequency:)])
[self.delegate startHeartDelegateRateFrequency:fre];
}
// 4.删除过期数据
for (int i = 0; i< 10; i++) {
[self.points removeObjectAtIndex:0];
}
}
}
