Differences

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--- internal:administration:idl [2025/11/27 11:56] – [general structure] jan
+++ internal:administration:idl [2026/03/19 20:55] (current) – [contour] jan
@@ Line 3071: / Line 3071: @@
   extrm_lev_max = +(machar()).xmax
-See function [[https://www.harrisgeospatial.com/docs/machar.html|function machar]].
+See function [[https://www.nv5geospatialsoftware.com/docs/MACHAR.html|function machar]].
@@ Line 3087: / Line 3087: @@
     /overplot
-Keyword c_annotations is used here toprovide a format - this is usually not necessary.
+Keyword c_annotations is used here to provide a format - this is usually not necessary.
 You can define also different thicknesses, colors etc. with the other %%c_...%% key words of %%contour%%
 see [[http://www.physics.nyu.edu/grierlab/idl_html_help/C40.html#wp908085| help for contour]].
+=== line patterns ===
+contour can draw hatch patterns - but note: the pattern is not transparent.
+  contour, z, x, y, $
+    levels = levels, $
+    c_orientation = [ 0 , 22, 45, 90, ... ] , $ ; orientation of the lines in degrees
+    c_spacing = [ 1, 0.5, 0.25, ... ] ; spacing between lines in cm
+=== Path of contour lines ===
+contour can provide the pathes of the contour lines:
+  contour, z, x, y, $
+    levels = levels, $
+    path_info = path_info, $ ; info about the provided pathes (see below). If you provide here a variable contour will not draw.
+    path_xy = path_xy, $ ; variable for coordinates: fltarr(2,N_tot)
+    /path_data_coords, $ ; want to have data coordinates in data_xy instead of normalized coo's.
+    /path_double, $ ; you need double if eg x is time as julian day
+    /overplot ; avoid contour to rescale the axes - if you already had a plot or contour plot you want to reuse
+path_info is an array of CONTOUR_PATH_STRUCTURE. The number of elelemtns gives the number of sub pathes.
+Elements %%offset%% and %%N%% give the starting index and length of every isoline in path_xy.
+You can then use the pathes in poly_fill to do transparent hatch patterns:
+  for i = 0, n_elements(path_info)-1 do begin
+    path_info_i = path_info[i]
+    ii = path_info_i.offset + lindgen(path_info_i.N)
+    polyfill, path_xy[0,ii], path_xy[1,ii], /line_fill, spacing=0.7, orientation=i*5, noclip=0
+  endfor ; i
+You could also use polyfill to put a byte pattern or wrap an image between the isolines ...
 === color bar ===
-You can use contour also to make a **color bar**:
+You may want to have a color bar setting the colorshading in relation to values.
+You can use contour to make a **color bar**:
 A **horizontal** color bar at the bottom