v.transects: Add categories of input lines to layer 2 of output

src/vector/v.transects/v.transects.html

@@ -40,6 +40,16 @@ <h2>NOTES</h2>
 <p>
 <em><b>v.transects</b></em> may fail for a network of lines in Windows.
 
+<p>The categories of the input lines are stored in layer 2 of the output. To upload them
+ to the transects table, use v.to.db like this:
+ <br>
+ <div class=code><pre>
+v.transects input=lines output=transects transect_spacing=100
+v.db.addtable transects columns="line_cat"
+v.db.addtable transects layer=2
+v.to.db transects query_layer=2 query_column=cat option=query column=line_cat
+ </pre></div>
+
 <h2>EXAMPLES</h2>
 
 In these examples, the

src/vector/v.transects/v.transects.py

@@ -46,6 +46,7 @@
 # %end
 # %option G_OPT_V_TYPE
 # % multiple: no
+# % label: Output type
 # % options: point,line,area
 # % answer: line
 # %end
@@ -120,17 +121,20 @@ def loadVector(vector):
  while ":" in vectorAscii[l]:
  l += 1
  v = []
+ cats = []
  while l < len(vectorAscii):
  line = vectorAscii[l].split()
  if line[0] in ["L", "B", "A"]:
- skip = len(line) - 2
+ ncat = int(line[2]) if len(line) > 2 else 0
  vertices = int(line[1])
  l += 1
  v.append([])
  for i in range(vertices):
  v[-1].append(list(map(float, vectorAscii[l].split()[:2])))
  l += 1
- l += skip
+ if ncat > 0:
+ cats += [vectorAscii[l].split()[1]]
+ l += ncat
  elif line[0] in ["P", "C", "F", "K"]:
  skip = len(line) - 2
  vertices = int(line[1])
@@ -142,7 +146,7 @@ def loadVector(vector):
  grass.fatal(_("Problem with line: <%s>") % vectorAscii[l])
  if len(v) < 1:
  grass.fatal(_("Zero lines found in vector map <%s>") % vector)
- return v
+ return v, cats
 
 
 def get_transects_locs(vector, transect_spacing, dist_function, last_point):
@@ -184,9 +188,9 @@ def get_transect_ends(transect_locs, vectors, trend, dleft, dright):
  if not trend:
  for k, transect in enumerate(transect_locs):
  # if a line in input vec was shorter than transect_spacing
+ transect_ends.append([])
  if len(transect) < 2:
  continue # then don't put a transect on it
- transect_ends.append([])
  transect = array(transect)
  v = NR(*vectors[k][0]) # vector pointing parallel to transect
  transect_ends[-1].append(
@@ -200,9 +204,9 @@ def get_transect_ends(transect_locs, vectors, trend, dleft, dright):
  else:
  for transect in transect_locs:
  # if a line in input vec was shorter than transect_spacing
+ transect_ends.append([])
  if len(transect) < 2:
  continue # then don't put a transect on it
- transect_ends.append([])
  transect = array(transect)
  v = NR(transect[0], transect[1]) # vector pointing parallel to transect
  transect_ends[-1].append(
@@ -240,20 +244,30 @@ def NR(ip, fp):
  return array([-y / r, x / r])
 
 
-def writeTransects(transects, output):
+def writeTransects(transects, cats, output):
  """!Writes transects."""
  transects_str = ""
- for transect in transects:
+ ncats = 2 if cats else 1
+ cat = 1
+ linecat = True if cats else ''
+ for i, transect in enumerate(transects):
+ if len(transect) == 0:
+ continue
+ # add line category in layer 2
+ if linecat:
+ linecat = "2 %s\n" % cats[i]
  transects_str += "\n".join(
  [
- "L 2\n"
+ "L 2 %s\n" % ncats
  + " ".join(map(str, end_points[0]))
  + "\n"
  + " ".join(map(str, end_points[1]))
  + "\n"
- for end_points in transect
+ + "1 %s \n%s" % (cat + ii, linecat)
+ for ii, end_points in enumerate(transect)
  ]
  )
+ cat += len(transect)
  # JL Rewrote Temporary File Logic for Windows
  _, temp_path = tempfile.mkstemp()
  a = open(temp_path, "w")
@@ -270,6 +284,8 @@ def writeQuads(transects, output):
  quad_str = ""
  cnt = 1
  for line in transects:
+ if len(line) == 0:
+ continue
  for tran in range(len(line) - 1):
  pt1 = " ".join(map(str, line[tran][0]))
  pt2 = " ".join(map(str, line[tran][1]))
@@ -378,7 +394,7 @@ def main():
  grass.fatal(_("vector <%s> does not contain lines") % vector)
 
  #################################
- v = loadVector(vector)
+ v, cats = loadVector(vector)
  if options["metric"] == "straight":
  dist = dist_euclidean
  else:
@@ -391,7 +407,7 @@ def main():
  temp_map = tempmap()
  if shape == "line" or not shape:
  transect_ends = get_transect_ends(transect_locs, vectors, trend, dleft, dright)
- writeTransects(transect_ends, temp_map)
+ writeTransects(transect_ends, cats, temp_map)
  elif shape == "area":
  transect_ends = get_transect_ends(transect_locs, vectors, trend, dleft, dright)
  writeQuads(transect_ends, temp_map)