[GRASS-SVN] r73260 - grass-addons/grass7/raster/r.stream.stats

[svn_grass at osgeo.org]

Author: wenzeslaus
Date: 2018-09-04 19:24:38 -0700 (Tue, 04 Sep 2018)
New Revision: 73260

Modified:
   grass-addons/grass7/raster/r.stream.stats/r.stream.stats.html
Log:
r.stream.stats: refs sec and minor improvements

Modified: grass-addons/grass7/raster/r.stream.stats/r.stream.stats.html
===================================================================
--- grass-addons/grass7/raster/r.stream.stats/r.stream.stats.html	2018-09-04 18:58:04 UTC (rev 73259)
+++ grass-addons/grass7/raster/r.stream.stats/r.stream.stats.html	2018-09-05 02:24:38 UTC (rev 73260)
@@ -53,8 +53,9 @@
 
 <h3>OUTPUTS</h3>
 
-Output statistics are send to standard output. To redirect output to
-file use redirection operators: <tt><</tt> or <tt><<</tt>
+Output statistics are send to standard output or to a file if specified
+using the <b>output</b> option. Aletrnatively, to redirect output to
+a file use redirection operators: <tt>></tt> or <tt>>></tt>
 (Unix only). If redirection is used, output messages are printed on
 stderr (usually terminal) while statistics are written to the file.
 Statistics can be print as a formatted summary information with number
@@ -64,13 +65,14 @@
 <h2>NOTES</h2>
 
 These statistics are calculated according to formulas given by
-R.Horton (1945). Because Horton do not defined precisely what is
-stream slope, 2 different approaches have been proposed: the first
-(slope) uses cell-by-cell slope calculation; the second (gradient)
+R. Horton (1945). Horton didn't define precisely what is
+stream slope, consequently 2 different approaches have been proposed.
+The first (slope) uses cell-by-cell slope calculation.
+The second (gradient)
 uses the difference between elevation of outlet and source of every
 channel to its length to calculate formula. Bifurcation ratio for
 every order is calculated acording to the formula:
-<tt>n_streams[1]/n_stream[i+1]</tt> where i is the current order
+<tt>n_streams[1]/n_stream[i+1]</tt> where <tt>i</tt> is the current order
 and <tt>i+1</tt> is the next higher order. For max order of the cell
 value of streams is zero. Rest of the ratios are calculated in similar
 mode. The bifurcation and other ratios for the whole catchment (map)
@@ -136,8 +138,8 @@
 following <em><a href="r.mapcalc.html">r.mapcalc</a></em> formula:
 
 <div class="code"><pre>
-#xxx category of desired basin
-r.mapcalc "sel_streams = if(basin==xxx,streams,null())"
+# xxx denotes the category of desired basin
+r.mapcalc "sel_streams = if(basin == xxx, streams, null())"
 </pre></div>
 
 <p>
@@ -144,14 +146,14 @@
 It is also possible to calculate Horton's statistics for Shreve
 ordering but it has no hydrological sense. Hack (or Gravelius
 hierarchy) main stream is not the same what so called Horton's reverse
-ordering (see: Horton 1945).
+ordering (see Horton 1945).
 
 <p>
 The module can work only if <b>direction</b> raster
 map, <b>stream_rast</b> map and region have the same settings. It is
-also required that stream_rast map and direction map come from the
+also required that <b>stream_rast</b> map and direction map come from the
 same source. For lots of reason this limitation probably cannot be
-omitted.  This means that if stream_rast map comes from
+omitted. This means that if <b>stream_rast</b> map comes from
 <em><a href="r.stream.extract.html">r.stream.extract</a></em> also
 direction map
 from <em><a href="r.stream.extract.html">r.stream.extract</a></em>
@@ -161,7 +163,8 @@
 <h2>EXAMPLE</h2>
 
 Create table with order statistics. This table can easily be sent to
-external program (like R) to be visualised:
+external program (like R) to be visualized (assuming a unix-like command
+line):
 
 <div class="code"><pre>
 g.region -p -a raster=elevation
@@ -171,15 +174,24 @@
 r.stream.stats -o stream_rast=horton direction=direction elevation=elevation > tmp_file
 
 R
-r=read.csv("tmp_file",skip=1,header=TRUE)
-plot(num_of_streams~order,data=r,log="y", 
-	main="Sperafish area", 
-	sub=paste("Bifurcation ratio: ",
-		round(1/10^model$coefficients[2],3)))
-model=lm(log10(num_of_streams)~order,data=r)
+# now in R
+r=read.csv("tmp_file", skip=1, header=TRUE)
+plot(num_of_streams~order, data=r, log="y", 
+     main="Sperafish area", 
+     sub=paste("Bifurcation ratio: ",
+               round(1/10^model$coefficients[2], 3)))
+model=lm(log10(num_of_streams)~order, data=r)
 abline(model)
 </pre></div>
 
+<h2>REFERENCES</h2>
+
+<ul>
+<li>Horton, R. E. (1945), <i>Erosional development of streams and their drainage
+basins: hydro-physical approach to quantitative morphology</i>, Geological
+Society of America Bulletin 56 (3): 275-370
+</ul>
+
 <h2>SEE ALSO</h2>
 
 <em>
@@ -204,4 +216,3 @@
 
 <p>
 <i>Last changed: $Date$</i>
-