Tips and Tricks - Revision history

⚠️Vincent: /* Quick tips */

2013-05-10T08:47:25Z

Quick tips

← Older revision		Revision as of 08:47, 10 May 2013
Line 88:		Line 88:
	==Quick tips ==		==Quick tips ==

	=== Checking categories ~~pertainig~~ to more than one feature ===		=== Checking categories pertaining to more than one feature ===
	<!--====Discover multiple features having the same category====-->		<!--====Discover multiple features having the same category====-->
	v.build op=cdump map=mymap \| gawk -F"\|" '{print $1}' \| uniq -dc		v.build op=cdump map=mymap \| gawk -F"\|" '{print $1}' \| uniq -dc
Line 94:		Line 94:
	5 35347<br />		5 35347<br />
	(5 features with cat 35347)		(5 features with cat 35347)


			=== Applying [[v.edit]] tools on a whole map ===
			[[v.edit]] allows many powerful geometrical manipulations. Operations are performed on certain features you must point out with arguments like ''ids='', ''cats='', ''coords='', and so on. When you need to run a tool on the whole map (e.g. every boundary), then it can be annoying to describe them (e.g. provide a ''cats'' list). A common way is to use the -r (reverse selection) flag in combination with pointing at feature-ids equal to zero (i.e. empty selection) :
			v.edit map=mymap type=boundary tool=merge ids=0 -r


	=== Compensate the lack of line ends symbology in ps.map ===		=== Compensate the lack of line ends symbology in ps.map ===

⚠️HamishBowman: /* Compensate the lack of line ends symbology in ps.map */ formatting

2013-03-03T20:55:32Z

Compensate the lack of line ends symbology in ps.map: formatting

← Older revision		Revision as of 20:55, 3 March 2013
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	The next example illustrates the process for line vector ''mylines''. We want to be able to draw an arrow head at the to-node lines for which attribute ''code'' equals 3 or 5 :		The next example illustrates the process for line vector ''mylines''. We want to be able to draw an arrow head at the to-node lines for which attribute ''code'' equals 3 or 5 :
	<~~pre~~>		<source lang="bash">
	for i in `v.out.ascii input=mylines format=standard where="code=3 or code=5" \		for i in `v.out.ascii input=mylines format=standard where="code=3 or code=5" \
	\| grep -n 'L ' \| sed s/\:/' '/ \| sed s/' '/' '/ \| awk '{print $1+$3-1}'`; \		\| grep -n 'L ' \| sed s/\:/' '/ \| sed s/' '/' '/ \| awk '{print $1+$3-1}'`; do
	do v.out.ascii input=mylines format=standard where="code=3 or code=5" \		v.out.ascii input=mylines format=standard where="code=3 or code=5" \
	\| sed -n ${i},$((i+2))p \| awk 'NR == 2 {x=$1;y=$2} NR == 1 {xi=$1;yi=$2} \		\| sed -n ${i},$((i+2))p \| \
	NR == 3 {cat=$2} END {pi=3.14159;OFS="\|";\		awk \
	print cat,x,y,atan2(yi-y,xi-x)/pi*180}'; done \		'NR == 2 {x=$1;y=$2} NR == 1 {xi=$1;yi=$2} \
	\| v.in.ascii -n out=myarrowheads x=2 y=3 cat=1 \		NR == 3 {cat=$2} END {pi=3.14159;OFS="\|"; \
	columns='cat int, x double precision, y double precision, angle double precision'		print cat,x,y,atan2(yi-y,xi-x)/pi*180}';
	</~~pre~~>		done \
			\| v.in.ascii -n out=myarrowheads x=2 y=3 cat=1 \
			columns='cat int, x double precision, y double precision, angle double precision'
			</source>

	''Warning: intended to be a set of piped commands, it does not handle temporary maps/files. Obvioulsly it is not an optimized solution in terms of calculations (v.out.ascii is run within the loop as many times as the number of processed lines). But it is reasonably fast and leaves no traces when completed.''		''Warning: intended to be a set of piped commands, it does not handle temporary maps/files. Obvioulsly it is not an optimized solution in terms of calculations (v.out.ascii is run within the loop as many times as the number of processed lines). But it is reasonably fast and leaves no traces when completed.''

⚠️Vincent: /* Compensate the lack of line ends symbology in ps.map */

2013-03-03T17:37:28Z

Compensate the lack of line ends symbology in ps.map

← Older revision		Revision as of 17:37, 3 March 2013
Line 109:		Line 109:
	columns='cat int, x double precision, y double precision, angle double precision'		columns='cat int, x double precision, y double precision, angle double precision'
	</pre>		</pre>

			''Warning: intended to be a set of piped commands, it does not handle temporary maps/files. Obvioulsly it is not an optimized solution in terms of calculations (v.out.ascii is run within the loop as many times as the number of processed lines). But it is reasonably fast and leaves no traces when completed.''

	It results in a point vector named ''myarrowheads''. Attribute field ''angle'' contains the rotation angle value fitting with to-node last segment direction.		It results in a point vector named ''myarrowheads''. Attribute field ''angle'' contains the rotation angle value fitting with to-node last segment direction.

⚠️Vincent: /* Compensate the lack of line ends symbology in ps.map */

2013-03-03T17:32:28Z

Compensate the lack of line ends symbology in ps.map

← Older revision		Revision as of 17:32, 3 March 2013
Line 96:		Line 96:

	=== Compensate the lack of line ends symbology in ps.map ===		=== Compensate the lack of line ends symbology in ps.map ===
	[[ps.map]] does not allow to specify line-end (from- and to-nodes) symbols oriented in the same direction as the last (resp. first) segment. Typically you want to add arrowheads to a line vector. Here we suggest a one-line gas (grep/awk/sed) solution. The idea is to output a bunch of selected lines ("where" argument), extract concerned couples of vertices, calculate a position and an angle for each tip, then import this set of data in a point vector. This point vector can latter be invoked in a command file.		[[ps.map]] does not allow to specify line-end (from- and to-nodes) symbols oriented in the same direction as the last (resp. first) segment. Typically you want to add arrowheads to a line vector. Here we suggest a one-line gas (grep/awk/sed) solution. The idea is to output a bunch of selected lines ("where" argument), extract concerned couples of vertices, calculate a position and an angle for each tip, then import this set of data in a point vector. This point vector can latter be invoked in a ps.map command file.

	The next example illustrates the process for line vector ''mylines''. We want to be able to draw an arrow head at the to-node lines for which attribute ''code'' equals 3 or 5 :		The next example illustrates the process for line vector ''mylines''. We want to be able to draw an arrow head at the to-node lines for which attribute ''code'' equals 3 or 5 :

⚠️Vincent: /* Compensate the lack of line ends symbology in ps.map */

2013-03-03T17:29:57Z

Compensate the lack of line ends symbology in ps.map

← Older revision		Revision as of 17:29, 3 March 2013
Line 100:		Line 100:
	The next example illustrates the process for line vector ''mylines''. We want to be able to draw an arrow head at the to-node lines for which attribute ''code'' equals 3 or 5 :		The next example illustrates the process for line vector ''mylines''. We want to be able to draw an arrow head at the to-node lines for which attribute ''code'' equals 3 or 5 :
	<pre>		<pre>
	for i in `v.out.ascii input=mylines format=standard where='code=3 or code=5' \		for i in `v.out.ascii input=mylines format=standard where="code=3 or code=5" \
	\| grep -n 'L ' \| sed s/\:/' '/ \| sed s/' '/' '/ \| awk '{print $1+$3-1}'`; \		\| grep -n 'L ' \| sed s/\:/' '/ \| sed s/' '/' '/ \| awk '{print $1+$3-1}'`; \
	do v.out.ascii input=mylines format=standard \| sed -n ${i},$((i+2))p \		do v.out.ascii input=mylines format=standard where="code=3 or code=5" \
	\| awk 'NR == 2 {x=$1;y=$2} NR == 1 {xi=$1;yi=$2} NR == 3 {cat=$2} END {pi=3.14159;OFS="\|";\		\| sed -n ${i},$((i+2))p \| awk 'NR == 2 {x=$1;y=$2} NR == 1 {xi=$1;yi=$2} \
			NR == 3 {cat=$2} END {pi=3.14159;OFS="\|";\
	print cat,x,y,atan2(yi-y,xi-x)/pi*180}'; done \		print cat,x,y,atan2(yi-y,xi-x)/pi*180}'; done \
	\| v.in.ascii -n out=myarrowheads x=2 y=3 cat=1 \		\| v.in.ascii -n out=myarrowheads x=2 y=3 cat=1 \

⚠️Vincent: /* Compensate the lack of line ends symbology in ps.map */

2013-03-03T16:35:50Z

Compensate the lack of line ends symbology in ps.map

← Older revision		Revision as of 16:35, 3 March 2013
Line 120:		Line 120:
	color black		color black
	symbol extra/n_arrow1		symbol extra/n_arrow1
	rotatecolumn angle		rotatecolumn angle+90
	size 2		size 2
	end		end
	</pre>		</pre>
	[[Category:Documentation]]		[[Category:Documentation]]

⚠️Vincent: /* Quick tips */ Added a one-line solution for arroheads problem within ps.map

2013-03-03T16:30:18Z

Quick tips: Added a one-line solution for arroheads problem within ps.map

← Older revision		Revision as of 16:30, 3 March 2013
Line 95:		Line 95:
	(5 features with cat 35347)		(5 features with cat 35347)

			=== Compensate the lack of line ends symbology in ps.map ===
			[[ps.map]] does not allow to specify line-end (from- and to-nodes) symbols oriented in the same direction as the last (resp. first) segment. Typically you want to add arrowheads to a line vector. Here we suggest a one-line gas (grep/awk/sed) solution. The idea is to output a bunch of selected lines ("where" argument), extract concerned couples of vertices, calculate a position and an angle for each tip, then import this set of data in a point vector. This point vector can latter be invoked in a command file.

			The next example illustrates the process for line vector ''mylines''. We want to be able to draw an arrow head at the to-node lines for which attribute ''code'' equals 3 or 5 :
			<pre>
			for i in `v.out.ascii input=mylines format=standard where='code=3 or code=5' \
			\| grep -n 'L ' \| sed s/\:/' '/ \| sed s/' '/' '/ \| awk '{print $1+$3-1}'`; \
			do v.out.ascii input=mylines format=standard \| sed -n ${i},$((i+2))p \
			\| awk 'NR == 2 {x=$1;y=$2} NR == 1 {xi=$1;yi=$2} NR == 3 {cat=$2} END {pi=3.14159;OFS="\|";\
			print cat,x,y,atan2(yi-y,xi-x)/pi*180}'; done \
			\| v.in.ascii -n out=myarrowheads x=2 y=3 cat=1 \
			columns='cat int, x double precision, y double precision, angle double precision'
			</pre>

			It results in a point vector named ''myarrowheads''. Attribute field ''angle'' contains the rotation angle value fitting with to-node last segment direction.

			ps.map command allowing to hardcopy arrows would look like this :
			<pre>
			vlines mylines
			width 0.6
			color black
			end
			vpoints myarrowheads
			color black
			symbol extra/n_arrow1
			rotatecolumn angle
			size 2
			end
			</pre>
	[[Category:Documentation]]		[[Category:Documentation]]

⚠️Marcocurreli: /* Quick tips */

2012-09-30T20:37:10Z

Quick tips

← Older revision		Revision as of 20:37, 30 September 2012
Line 86:		Line 86:
	Using the -X flag, or simply turning on X11Forwarding in the SSH configuration files, is not enough: the symptoms in this case are that a d.mon window will function fine, but none of the Tcl/Tk dialogues will work, failing with an error message complaining either about Wish not behaving as expected, or a "Bad Atom".		Using the -X flag, or simply turning on X11Forwarding in the SSH configuration files, is not enough: the symptoms in this case are that a d.mon window will function fine, but none of the Tcl/Tk dialogues will work, failing with an error message complaining either about Wish not behaving as expected, or a "Bad Atom".

	=== Quick tips ===		==Quick tips ==

	==== Checking categories pertainig to more than one feature ====		=== Checking categories pertainig to more than one feature ===
	<!--====Discover multiple features having the same category====-->		<!--====Discover multiple features having the same category====-->
	v.build op=cdump map=mymap \| gawk -F"\|" '{print $1}' \| uniq -dc		v.build op=cdump map=mymap \| gawk -F"\|" '{print $1}' \| uniq -dc

⚠️Marcocurreli: /* Tips and Tricks */ quick tips: checking categories pertainig to more than one feature

2012-09-27T23:38:08Z

Tips and Tricks: quick tips: checking categories pertainig to more than one feature

← Older revision		Revision as of 23:38, 27 September 2012
Line 86:		Line 86:
	Using the -X flag, or simply turning on X11Forwarding in the SSH configuration files, is not enough: the symptoms in this case are that a d.mon window will function fine, but none of the Tcl/Tk dialogues will work, failing with an error message complaining either about Wish not behaving as expected, or a "Bad Atom".		Using the -X flag, or simply turning on X11Forwarding in the SSH configuration files, is not enough: the symptoms in this case are that a d.mon window will function fine, but none of the Tcl/Tk dialogues will work, failing with an error message complaining either about Wish not behaving as expected, or a "Bad Atom".

			=== Quick tips ===

			==== Checking categories pertainig to more than one feature ====
			<!--====Discover multiple features having the same category====-->
			v.build op=cdump map=mymap \| gawk -F"\|" '{print $1}' \| uniq -dc
			returns, e.g.<br />
			5 35347<br />
			(5 features with cat 35347)

	[[Category:Documentation]]		[[Category:Documentation]]

Neteler: /* Using QGIS as a frontend to GRASS */

2010-10-10T18:51:24Z

Using QGIS as a frontend to GRASS

← Older revision		Revision as of 18:51, 10 October 2010
Line 36:		Line 36:
	While not a firm requirement, it is easier to start QGIS from within a GRASS session.		While not a firm requirement, it is easier to start QGIS from within a GRASS session.

	* [~~http://wiki.qgis.org/qgiswiki/GrassCookbook~~ QGIS GRASS Cookbook] - Recipes for common tasks		* [[QGIS GRASS Cookbook]] - Recipes for common tasks

	===Importing SRTM30plus data===		===Importing SRTM30plus data===