A new task allows taking a list of RA, Dec, and data, such as image names, that one wants to group into sublists. The grouping is based on a minimum separation in RA and Dec. The
SKYGROUP help page is available from this site already, the code itself is in the body of the message and in the upcoming release in the NPROTO package.
# SKYGROUP -- Group coordinate list on the sky.
#
# The input is list of ra (0h-24h or 0d-360d) and dec (-90d to 90d) in the
# first two columns followed by arbitrary data (usually a filename).
# This is complicated by the periodicities at 0h.
procedure skygroup (input, output)
file input {prompt="Input list"}
string output {prompt="Output rootname"}
string extn = "" {prompt="Optional output extension"}
real sep = 60 {prompt="Separation between groups (arcsec)"}
string raunit = "hr" {prompt="RA unit (hr|deg)"}
bool keepcoords = yes {prompt="Keep coordinates in output?"}
string raformat = "%.2h" {prompt="Output RA format"}
string decformat = "%.1h" {prompt="Output DEC format"}
struct *fd1, *fd2
begin
file in, out, fname, temp1, temp2, temp3
int i, j, n, n1
real dra, r1, d1, r2, d2, r3, d3, r4
struct fmtstr, data1, data2, data3
# Temporary files.
fname = mktemp ("tmp")
in = fname // "in"
temp1 = fname // "1"
temp2 = fname // "2"
temp3 = fname // "3"
# Set parameters.
fname = input
out = output
# Check for existing output files.
files (out//"_[0-9][0-9][0-9][0-9]*"//extn, > temp1)
count (temp1) | scan (n); delete (temp1, verify-)
if (access(out) || n > 0)
error (1, "Output files already exist")
if (raunit == "hr")
dra = 24
else
dra = 360
if (keepcoords)
fmtstr = "%d " // raformat // " " // decformat // " %s"
else
fmtstr = "%d %s"
fmtstr += "n"
# We start by sorting in dec.
sort (fname, col=2, num+, > in)
# Find jumps in dec bigger than the separation and then sort
# in ra and find jumps in ra bigger than separation. Handle
# the wrap around at 0h by duplicating to extend beyond 24h.
# The duplicates will be eliminated during the merging process.
n = 1
fd1 = in
if (fscan (fd1, r1, d1, data1) == EOF)
error (1, "No data or badly formated data")
while (fscan (fd1, r2, d2, data2) != EOF) {
print (r1, d1, data1, >> temp1)
if (r1 / max (0.001, dcos(d1)) * 3600 > temp1)
}
if (abs(d2-d1) temp2)
delete (temp1, verify-)
fd2 = temp2
if (fscan (fd2, r1, d1, data1) == EOF);
while (fscan (fd2, r2, d2, data2) != EOF) {
if (keepcoords)
printf (fmtstr, n, r1, d1, data1, >> temp3)
else
printf (fmtstr, n, data1, >> temp3)
skysep (r1, d1, r2, d2, raunit=raunit, verb-)
if (skysep.sep > temp3)
else
printf (fmtstr, n, data1, >> temp3)
n += 1
r1 = r3; d1 = d3; data1 = data3
} fd1 = ""; delete (in, verify-)
print (r1, d1, data1, >> temp1)
if (r1 / max (0.001, dcos(d1)) * 3600 > temp1)
}
sort (temp1, col=1, num+, > temp2)
delete (temp1, verify-)
fd2 = temp2
if (fscan (fd2, r1, d1, data1) == EOF);
while (fscan (fd2, r2, d2, data2) != EOF) {
if (keepcoords)
printf (fmtstr, n, r1, d1, data1, >> temp3)
else
printf (fmtstr, n, data1, >> temp3)
skysep (r1, d1, r2, d2, raunit=raunit, verb-)
if (skysep.sep > temp3)
else
printf (fmtstr, n, data1, >> temp3)
# Now write out the lists and check for duplicate which must be
# merged.
sort (temp3, col=1, num+, > temp1); delete (temp3, verify-)
touch (temp2)
fd1 = temp1
if (fscan (fd1, i, data1) == EOF);
while (fscan (fd1, j, data2) != EOF) {
if (data1 == data2) {
print (j, i, >> temp2)
next
}
printf ("%s_%03d%sn", out, i, extn) | scan (fname)
print (data1, >> fname)
i = j; data1 = data2
}
fd1 = ""; delete (temp1, verify-)
printf ("%s_%03d%sn", out, i, extn) | scan (fname)
print (data1, >> fname)
sort (temp2, col=1, num+, rev+) | unique (> temp1)
delete (temp2, verify-)
# Merge the lists.
n1 = n
fd1 = temp1
while (fscan (fd1, j, i) != EOF) {
printf ("%s_%03d%sn", out, j, extn) | scan (fname)
if (access (fname)) {
printf ("%s_%03d%sn", out, i, extn) | scan (in)
concat (in, fname, append+)
delete (in, verify-)
n1 -= 1
}
}
fd1 = ""; delete (temp1, verify-)
# Renumber if needed.
if (n1 != n) {
i = 1
for (j=1; j out//extn)
end