1 files changed, 124 insertions, 0 deletions
diff --git a/src/current/tools/csvi b/src/current/tools/csvi
new file mode 100755
index 0000000..08d80e2
--- /dev/null
+++ b/src/current/tools/csvi
@@ -0,0 +1,124 @@
+#!/usr/bin/awk -f
+#
+# Performs interpolation for columns in a CSV and outputs the result
+#
+# Configurable values (use -vname=value from command line):
+#   step  - use predeterminated step instead of calculating from first two rows
+#
+# #
+
+function storeline()
+{
+  for ( i = 1; i <= hlen; i++ ) {
+    prev[i] = $i
+  }
+}
+
+function clearline()
+{
+  for ( i = 1; i <= hlen; i++ ) {
+    prev[i] = 0
+  }
+}
+
+function getprev()
+{
+  for ( i = 1; i <= hlen; i++ ) {
+    $i = prev[i]
+  }
+}
+
+
+function interpolate()
+{
+  lastval = prev[1]
+
+  curval = $1
+  diff = curval - lastval
+
+  # does this value fall in line with the requested step?
+  if ( diff == step )
+  {
+    storeline()
+
+    # we're good; continue
+    print
+    next
+  }
+
+  # if we do not yet have a value large enough to reach our step, then continue
+  # until we do (do not store this line)
+  n = int( diff / step )
+  if ( n <= 0 ) {
+    next
+  }
+
+  # determine interpolation values
+  for ( i = 2; i <= hlen; i++ ) {
+    ival[i] = ( ( $i - prev[i] ) / n )
+  }
+
+  getprev()
+
+  # let us interpolate values that are divisible by the step
+  do
+  {
+    # increase the last value by our step
+    $1 += step
+
+    # interpolate each column value (notice that we skip the first column, which
+    # was handled directly above)
+    for ( i = 2; i <= hlen; i++ ) {
+      $i += ival[i]
+    }
+
+    # print the new line
+    print
+  } while ( ( diff -= step ) > 0 )
+
+  # anything remaining does not fit into our step and will be ignored; we'll
+  # continue with our next step at the next line
+
+  # consider this to be our last line
+  storeline()
+}
+
+
+BEGIN {
+  # the first row of the CSV is the header representing the column identifiers
+  getline
+  hlen = split( $0, header, /,/ )
+
+  # output the header
+  print $0
+
+  # delimit fields by commas (the field separator for CSVs); note that this
+  # won't work properly if strings contain commas
+  FS = OFS = ","
+
+  clearline()
+  getline
+
+  # if no step was provided, then calculate one based on the first two rows
+  if ( step == 0 ) {
+    # output the first row, which does not need to be interpolated
+    print
+
+    # compute the step
+    vala = $1
+    getline
+    valb = $1
+    step = valb - vala
+
+    # since the second line is used to determine the step, then it must match the
+    # step and therefore is good to output
+    print
+
+    # begin.
+    storeline()
+  }
+}
+
+
+# for each row
+{ interpolate() }