stats.hoc

// $Id: stats.hoc,v 1.7 2012/07/20 15:09:22 samn Exp $ 

print "Loading stats.hoc..."

//based on code from:
//http://pdos.csail.mit.edu/grid/sim/capacity-ns.tgz/capacity-sim/new-ns/
//hoc template that allows sampling from a pareto power law distribution 
//specified with objref rd
//rd = new rdmpareto($1=avg,$2=shape,[$3=seed])
//then picking values with .pick , or assigning to a vec with assignv(vec)
begintemplate rdmpareto
public avg,shape,rd,seed,pick,repick,paretoc,pareto5,assignv,reset,pareto4,pareto3
double avg[1],shape[1],seed[1]
objref rd
proc init () {
  avg=$1 shape=$2
  if(numarg()>2)seed=$3 else seed=1234
  rd=new Random()
  rd.ACG(seed)
}
proc reset () {
  rd.ACG(seed)
}
func paretoc () { local scale,shape,U
  scale=$1 shape=$2 U = rd.uniform(0,1)
  return scale * (1.0/ U^(1/shape) )
}
func pareto5 () { local avg,shape
  avg=$1 shape=$2
  return paretoc( avg * (shape -1)/shape, shape)
}
func pareto4 () { local alpha,u
  alpha=$2
  u = 1 - rd.uniform(0,1)
  return $1 + 1 / u^(1/alpha)
}
func pareto3 () { local x,z,b,a
  b = avg // 1 //min value
  a = shape // 10
  x = rd.uniform(0,1)
  z = x^-1/a
  return 1 + b * z
}
func pick () {
  return pareto5(avg,shape)
}
func repick () {
  return pick()
}
func assignv () { local i localobj vi
  vi=$o1 
  for i=0,vi.size-1 vi.x(i)=pick()
}
endtemplate rdmpareto

func skew () { local a,ret localobj v1
  a=allocvecs(v1)
  $o1.getcol($s2).moment(v1)
  ret=v1.x[4]
  dealloc(a)
  return ret
}

func skewv () { localobj v1
  v1=new Vector(5)
  $o1.moment(v1)
  return v1.x(4)
}


//** test rsampsig
objref vIN0,vIN1,vhsout,myrdm,vrs,VA
R0SZ=30000//size of group 0
R1SZ=30000//size of group 1
RPRC=100 // # of trials (combinations)
RS0M=0 //mean of group 0
RS1M=0 //mean of group 1
RS0SD=1 //sdev of group 0
RS1SD=1 //sdev of group 1
proc rsi () {
  if(myrdm==nil) myrdm=new Random()  
  {myrdm.normal(RS0M,RS0SD) vIN0=new Vector(R0SZ) vIN0.setrand(myrdm)}  
  {myrdm.normal(RS1M,RS1SD) vIN1=new Vector(R1SZ) vIN1.setrand(myrdm)}
  vhsout=new Vector(vIN0.size+vIN1.size)
  if(RPRC>1){
    vrs=new Vector(RPRC)
  } else {
    vrs=new Vector(combs_stats(R0SZ+R1SZ,mmax(R0SZ,R1SZ))*RPRC)
  }
  VA=new Vector()  VA.copy(vIN0) VA.append(vIN1)
}
func hocmeasure () {
  hretval_stats=vhsout.mean
  return vhsout.mean
}
func compfunc () {
  if(verbose_stats>1) printf("$1=%g,$2=%g\n",$1,$2)
  hretval_stats=$1-$2
  return hretval_stats
}
onesided=0
nocmbchk=1
pval=tval=0
func testrs () { local dd localobj str
  if(numarg()>0)dd=$1 else dd=1
  str=new String()
  rsi()
  vhsout.resize(vIN0.size+vIN1.size)
  pval=vrs.rsampsig(vIN0,vIN1,RPRC,"hocmeasure","compfunc",vhsout,onesided,nocmbchk)
  tval=ttest(vIN0,vIN1)
  if(dd){
    sprint(str.s,"p(abs(m0-m1))>%g=%g, t=%g, e=%g",abs(vIN0.mean-vIN1.mean),pval,tval,abs(pval-tval)/tval)
    {ge() ers=0 clr=1 hist(g,VA) clr=2  hist(g,vIN0) clr=3  hist(g,vIN1) g.label(0,0.95,str.s)}
    sprint(str.s,"m0=%g, m1=%g, n0=%g, n1=%g, s0=%g, s1=%g",vIN0.mean,vIN1.mean,vIN0.size,vIN1.size,vIN0.stdev,vIN1.stdev)
    g.label(0.0,0.0,str.s)
    sprint(str.s,"m0-m1=%g",vIN0.mean-vIN1.mean)
    g.label(0,0.9,str.s)
    g.exec_menu("View = plot")
  }
  printf("pval=%g, tval=%g, err=%g\n",pval,tval,abs(pval-tval)/tval)
  return pval
}

//* nhppvec(intensityvec,dt,maxt[,se])
// returns a Vector of spike times generated by a nonhomogenous poisson process
// described by intensity function intensityvec, with dt time-step, maxt max time
// and se the seed for random # generator
// this algorithm is called 'thinning'
obfunc nhppvec () { local i,dt,tt,maxt,maxi,se,tidx localobj tvec,ivec,rdm
  tvec=new Vector(100e3) tvec.resize(0)
  ivec=$o1 dt=$2 maxt=$3
  if(numarg()>3)se=$4 else se=1234
  rdm=new Random()
  rdm.ACG(se)
  tt=0
  maxi=ivec.max
  while(tt<maxt) {
    tt = tt - 1.0/maxi * log(rdm.uniform(0,1))
    tidx = tt / dt
    if(tidx >= ivec.size) break
    if(rdm.uniform(0,1) <= ivec.x(tidx) / maxi) {
      tvec.append(tt)
    }
  }
  return tvec
}

//* cvpsync(vector of spike times, N == number of neurons)
// this function calculates the spike-train synchrony on a population of N neurons, as
// proposed by tiesinga & sejnowski in /u/samn/papers/nc_16_251.pdf .
// the function returns a number ranging from 0 to 1
//with 0 for asynchronous activity and 1 for synchronous.
func cvpsync () { local i,cvp,N,X,X2,sz,a localobj vt,vint
  a=allocvecs(vt,vint)
  {vt.copy($o1) vt.sort() vint.resize(vt.size) vint.resize(0) N = $2}
  if(N < 1) return 0
  sz = vt.size()
  if(sz < 2) return 0
  vint.deriv(vt,1,1) // gets ISI (interspike intervals)
  X = vint.sum()/sz
  if(X <= 0) return 0
  X2 = vint.sumsq()/sz
  cvp = sqrt( X2 - X^2 ) / X
  dealloc(a)
  return (cvp - 1.0) / sqrt(N)
}