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include <smw.h>
include "icombine.h"
# IC_STATR -- Compute image statistics within spectrum.
procedure ic_statr (sh, lflag, rg, domode, domedian, domean, mode, median, mean)
pointer sh # Spectrum structure
int lflag # Data flag
pointer rg # Wavelength ranges
bool domode, domedian, domean # Statistics to compute
real mode, median, mean # Statistics
int i, n, npts
real a, w
pointer sp, data, dp, lp, mp
real ic_moder(), asumr()
bool ic_wisinrange()
double shdr_lw()
include "icombine.com"
begin
mp = SX(sh)
lp = SY(sh)
npts = SN(sh)
call smark (sp)
call salloc (data, npts, TY_REAL)
dp = data
if (lflag == D_ALL && rg == NULL) {
if (dothresh) {
do i = 1, npts {
a = Memr[lp]
if (a >= lthresh && a <= hthresh) {
Memr[dp] = a
dp = dp + 1
}
lp = lp + 1
}
} else {
do i = 1, npts {
Memr[dp] = Memr[lp]
dp = dp + 1
lp = lp + 1
}
}
} else if (lflag == D_MIX || rg != NULL) {
if (dothresh) {
do i = 1, npts {
if (Memr[mp] == 0) {
a = Memr[lp]
if (a >= lthresh && a <= hthresh) {
w = shdr_lw (sh, double (i))
if (ic_wisinrange (rg, w)) {
Memr[dp] = a
dp = dp + 1
}
}
}
mp = mp + 1
lp = lp + 1
}
} else {
do i = 1, npts {
if (Memr[mp] == 0) {
w = shdr_lw (sh, double (i))
if (ic_wisinrange (rg, w)) {
Memr[dp] = Memr[lp]
dp = dp + 1
}
}
mp = mp + 1
lp = lp + 1
}
}
}
n = dp - data
if (n > 0) {
# Compute only statistics needed.
if (domode || domedian) {
call asrtr (Memr[data], Memr[data], n)
mode = ic_moder (Memr[data], n)
median = Memr[data+n/2-1]
}
if (domean)
mean = asumr (Memr[data], n) / n
} else {
mode = INDEF
median = INDEF
mean = INDEF
}
call sfree (sp)
end
define NMIN 10 # Minimum number of pixels for mode calculation
define ZRANGE 0.8 # Fraction of pixels about median to use
define ZSTEP 0.01 # Step size for search for mode
define ZBIN 0.1 # Bin size for mode.
# IC_MODE -- Compute mode of an array. The mode is found by binning
# with a bin size based on the data range over a fraction of the
# pixels about the median and a bin step which may be smaller than the
# bin size. If there are too few points the median is returned.
# The input array must be sorted.
real procedure ic_moder (a, n)
real a[n] # Data array
int n # Number of points
int i, j, k, nmax
real z1, z2, zstep, zbin
real mode
bool fp_equalr()
begin
if (n < NMIN)
return (a[n/2])
# Compute the mode. The array must be sorted. Consider a
# range of values about the median point. Use a bin size which
# is ZBIN of the range. Step the bin limits in ZSTEP fraction of
# the bin size.
i = 1 + n * (1. - ZRANGE) / 2.
j = 1 + n * (1. + ZRANGE) / 2.
z1 = a[i]
z2 = a[j]
if (fp_equalr (z1, z2)) {
mode = z1
return (mode)
}
zstep = ZSTEP * (z2 - z1)
zbin = ZBIN * (z2 - z1)
z1 = z1 - zstep
k = i
nmax = 0
repeat {
z1 = z1 + zstep
z2 = z1 + zbin
for (; i < j && a[i] < z1; i=i+1)
;
for (; k < j && a[k] < z2; k=k+1)
;
if (k - i > nmax) {
nmax = k - i
mode = a[(i+k)/2]
}
} until (k >= j)
return (mode)
end
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