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# UNIQUE -- Find unique rows in a table
#
# First, the table is sorted on columns input in the colptr array. The
# results are stored in the index array. Then each row in the index array
# is compared to the most recent unique row in the index array, column by
# column. If any column differs, the row is also considered to be unique.
# The index array is updated to reflect the new unique row and the number of
# unique rows is incremented.
#
# B.Simon 19-Oct-87 First Code
# B.Simon 14-Dec-87 Changed to handle table subsets
# B.Simon 06-Feb-90 Changed to use tbtsrt and tbrcmp
procedure unique (tp, numptr, colptr, nindex, index)
pointer tp # i: Table descriptor
int numptr # i: Number of column pointers
pointer colptr[ARB] # i: Array of column pointers
int nindex # io: Number of unique row indices returned
int index[ARB] # io: Array of unique indices
#--
bool fold
int order, idx, jdx, n, i
int tbrcmp()
begin
# Sort the array on the selected columns. The sort is in ascending
# order and case sensitive
fold = false
call tbtsrt (tp, numptr, colptr, fold, nindex, index)
# Search for unique rows
jdx = 0
n = nindex
nindex = 0
do i = 1, n {
idx = index[i]
# First row is always unique
if (i == 1)
order = 1
else
order = tbrcmp (tp, numptr, colptr, fold, idx, jdx)
# Update pointer to most recent unique row and modify index
# array in place
if (order != 0) {
jdx = idx
nindex = nindex + 1
index[nindex] = idx
}
}
do i = nindex+1, n
index[i] = 0
end
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