diff options
Diffstat (limited to 'pyspike/cython_distance.pyx')
| -rw-r--r-- | pyspike/cython_distance.pyx | 148 |
1 files changed, 142 insertions, 6 deletions
diff --git a/pyspike/cython_distance.pyx b/pyspike/cython_distance.pyx index 330eea4..1a6d24a 100644 --- a/pyspike/cython_distance.pyx +++ b/pyspike/cython_distance.pyx @@ -3,8 +3,17 @@ #cython: cdivision=True """ -Doc +cython_distances.py +cython implementation of the isi- and spike-distance + +Note: using cython memoryviews (e.g. double[:]) instead of ndarray objects +improves the performance of spike_distance by a factor of 10! + +Copyright 2014, Mario Mulansky <mario.mulansky@gmx.net> +""" + +""" To test whether things can be optimized: remove all yellow stuff in the html output:: @@ -14,20 +23,25 @@ which gives:: cython_distance.html - """ import numpy as np cimport numpy as np +from libc.math cimport fabs + DTYPE = np.float ctypedef np.float_t DTYPE_t -def isi_distance_cython(np.ndarray[DTYPE_t, ndim=1] s1, np.ndarray[DTYPE_t, ndim=1] s2): - cdef np.ndarray[DTYPE_t, ndim=1] spike_events - # the values have one entry less - the number of intervals between events - cdef np.ndarray[DTYPE_t, ndim=1] isi_values +############################################################ +# isi_distance_cython +############################################################ +def isi_distance_cython(double[:] s1, + double[:] s2): + + cdef double[:] spike_events + cdef double[:] isi_values cdef int index1, index2, index cdef int N1, N2 cdef double nu1, nu2 @@ -38,6 +52,7 @@ def isi_distance_cython(np.ndarray[DTYPE_t, ndim=1] s1, np.ndarray[DTYPE_t, ndim nu2 = s2[1]-s2[0] spike_events = np.empty(N1+N2) spike_events[0] = s1[0] + # the values have one entry less - the number of intervals between events isi_values = np.empty(N1+N2-1) isi_values[0] = (nu1-nu2)/max(nu1,nu2) index1 = 0 @@ -73,3 +88,124 @@ def isi_distance_cython(np.ndarray[DTYPE_t, ndim=1] s1, np.ndarray[DTYPE_t, ndim spike_events[index] = s1[N1] return spike_events[:index+1], isi_values[:index] + + +############################################################ +# get_min_dist_cython +############################################################ +cdef inline double get_min_dist_cython(double spike_time, + double[:] spike_train, + # use memory view to ensure inlining + # np.ndarray[DTYPE_t,ndim=1] spike_train, + int N, + int start_index=0): + """ Returns the minimal distance |spike_time - spike_train[i]| + with i>=start_index. + """ + cdef double d, d_temp + d = fabs(spike_time - spike_train[start_index]) + start_index += 1 + while start_index < N: + d_temp = fabs(spike_time - spike_train[start_index]) + if d_temp > d: + break + else: + d = d_temp + start_index += 1 + return d + + +############################################################ +# spike_distance_cython +############################################################ +def spike_distance_cython(double[:] t1, + double[:] t2): + + cdef double[:] spike_events + cdef double[:] y_starts + cdef double[:] y_ends + + cdef int N1, N2, index1, index2, index + cdef double dt_p1, dt_p2, dt_f1, dt_f2, isi1, isi2, s1, s2 + + N1 = len(t1) + N2 = len(t2) + + spike_events = np.empty(N1+N2-2) + spike_events[0] = t1[0] + y_starts = np.empty(len(spike_events)-1) + y_ends = np.empty(len(spike_events)-1) + + index1 = 0 + index2 = 0 + index = 1 + dt_p1 = 0.0 + dt_f1 = get_min_dist_cython(t1[1], t2, N2, 0) + dt_p2 = 0.0 + dt_f2 = get_min_dist_cython(t2[1], t1, N1, 0) + isi1 = max(t1[1]-t1[0], t1[2]-t1[1]) + isi2 = max(t2[1]-t2[0], t2[2]-t2[1]) + s1 = dt_f1*(t1[1]-t1[0])/isi1 + s2 = dt_f2*(t2[1]-t2[0])/isi2 + y_starts[0] = (s1*isi2 + s2*isi1) / ((isi1+isi2)**2/2) + while True: + # print(index, index1, index2) + if t1[index1+1] < t2[index2+1]: + index1 += 1 + # break condition relies on existence of spikes at T_end + if index1+1 >= N1: + break + spike_events[index] = t1[index1] + # first calculate the previous interval end value + dt_p1 = dt_f1 # the previous time now was the following time before + s1 = dt_p1 + s2 = (dt_p2*(t2[index2+1]-t1[index1]) + dt_f2*(t1[index1]-t2[index2])) / isi2 + y_ends[index-1] = (s1*isi2 + s2*isi1) / ((isi1+isi2)**2/2) + # now the next interval start value + dt_f1 = get_min_dist_cython(t1[index1+1], t2, N2, index2) + isi1 = t1[index1+1]-t1[index1] + # s2 is the same as above, thus we can compute y2 immediately + y_starts[index] = (s1*isi2 + s2*isi1) / ((isi1+isi2)**2/2) + elif t1[index1+1] > t2[index2+1]: + index2 += 1 + if index2+1 >= N2: + break + spike_events[index] = t2[index2] + # first calculate the previous interval end value + dt_p2 = dt_f2 # the previous time now was the following time before + s1 = (dt_p1*(t1[index1+1]-t2[index2]) + dt_f1*(t2[index2]-t1[index1])) / isi1 + s2 = dt_p2 + y_ends[index-1] = (s1*isi2 + s2*isi1) / ((isi1+isi2)**2/2) + # now the next interval start value + dt_f2 = get_min_dist_cython(t2[index2+1], t1, N1, index1) + #s2 = dt_f2 + isi2 = t2[index2+1]-t2[index2] + # s2 is the same as above, thus we can compute y2 immediately + y_starts[index] = (s1*isi2 + s2*isi1) / ((isi1+isi2)**2/2) + else: # t1[index1+1] == t2[index2+1] - generate only one event + index1 += 1 + index2 += 1 + if (index1+1 >= N1) or (index2+1 >= N2): + break + spike_events[index] = t1[index1] + y_ends[index-1] = 0.0 + y_starts[index] = 0.0 + dt_p1 = 0.0 + dt_p2 = 0.0 + dt_f1 = get_min_dist_cython(t1[index1+1], t2, N2, index2) + dt_f2 = get_min_dist_cython(t2[index2+1], t1, N1, index1) + isi1 = t1[index1+1]-t1[index1] + isi2 = t2[index2+1]-t2[index2] + index += 1 + # the last event is the interval end + spike_events[index] = t1[N1-1] + # the ending value of the last interval + isi1 = max(t1[N1-1]-t1[N1-2], t1[N1-2]-t1[N1-3]) + isi2 = max(t2[N2-1]-t2[N2-2], t2[N2-2]-t2[N2-3]) + s1 = dt_p1*(t1[N1-1]-t1[N1-2])/isi1 + s2 = dt_p2*(t2[N2-1]-t2[N2-2])/isi2 + y_ends[index-1] = (s1*isi2 + s2*isi1) / ((isi1+isi2)**2/2) + # use only the data added above + # could be less than original length due to equal spike times + + return spike_events[:index+1], y_starts[:index], y_ends[:index] |