I need to optimise code that counts pos/neg values and remove non-qualified values by time.
I have queue of values with time-stamp attached.
I need to discard values which are 1ms old and count negative and positive values. here is pseudo code
list<val> l;
v = q.dequeue();
deleteold(l, v.time);
l.add(v);
negcount = l.count(i => i.value < 0);
poscount = l.count(i => i.value >= 0);
if(negcount == 10) return -1;
if(poscount == 10) return 1;
I need this code in c# working with max speed. No need to stick to the List. In fact arrays separated for neg and pos values are welcome.
edit: probably unsafe arrays will be the best. any hints?
EDIT: thanks for the heads up.. i quickly tested array version vs list (which i already have) and the list is faster: 35 vs 16 ms for 1 mil iterations...
Here is the code for fairness sake:
class Program
{
static int LEN = 10;
static int LEN1 = 9;
static void Main(string[] args)
{
Var[] data = GenerateData();
Stopwatch sw = new Stopwatch();
for (int i = 0; i < 30; i++)
{
sw.Reset();
ArraysMethod(data, sw);
Console.Write("Array: {0:0.0000}ms ", sw.ElapsedTicks / 10000.0);
sw.Reset();
ListMethod(data, sw);
Console.WriteLine("List: {0:0.0000}ms", sw.ElapsedTicks / 10000.0);
}
Console.ReadLine();
}
private static void ArraysMethod(Var[] data, Stopwatch sw)
{
int signal = 0;
int ni = 0, pi = 0;
Var[] n = new Var[LEN];
Var[] p = new Var[LEN];
for (int i = 0; i < LEN; i++)
{
n[i] = new Var();
p[i] = new Var();
}
sw.Start();
for (int i = 0; i < DATALEN; i++)
{
Var v = data[i];
if (v.val < 0)
{
int x = 0;
ni = 0;
// time is not sequential
for (int j = 0; j < LEN; j++)
{
long diff = v.time - n[j].time;
if (diff < 0)
diff = 0;
// too old
if (diff > 10000)
x = j;
else
ni++;
}
n[x] = v;
if (ni >= LEN1)
signal = -1;
}
else
{
int x = 0;
pi = 0;
// time is not sequential
for (int j = 0; j < LEN; j++)
{
long diff = v.time - p[j].time;
if (diff < 0)
diff = 0;
// too old
if (diff > 10000)
x = j;
else
pi++;
}
p[x] = v;
if (pi >= LEN1)
signal = 1;
}
}
sw.Stop();
}
private static void ListMethod(Var[] data, Stopwatch sw)
{
int signal = 0;
List<Var> d = new List<Var>();
sw.Start();
for (int i = 0; i < DATALEN; i++)
{
Var v = data[i];
d.Add(new Var() { time = v.time, val = v.val < 0 ? -1 : 1 });
// delete expired
for (int j = 0; j < d.Count; j++)
{
if (v.time - d[j].time < 10000)
d.RemoveAt(j--);
else
break;
}
int cnt = 0;
int k = d.Count;
for (int j = 0; j < k; j++)
{
cnt += d[j].val;
}
if ((cnt >= 0 ? cnt : -cnt) >= LEN)
signal = 9;
}
sw.Stop();
}
static int DATALEN = 1000000;
private static Var[] GenerateData()
{
Random r = new Random(DateTime.Now.Millisecond);
Var[] data = new Var[DATALEN];
Var prev = new Var() { val = 0, time = DateTime.Now.TimeOfDay.Ticks};
for (int i = 0; i < DATALEN; i++)
{
int x = r.Next(20);
data[i] = new Var() { val = x - 10, time = prev.time + x * 1000 };
}
return data;
}
class Var
{
public int val;
public long time;
}
}