# Add a grid to your graphs **URL:** \ **Category:** Show and Tell\ **Created:** [August 18, 2024, 8:39pm UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402 "2024-08-18T20:39:05Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![steveroush](https://avatars.discourse-cdn.com/v4/letter/s/a9adbd/32.png) [@steveroush](https://forum.graphviz.org/u/steveroush)\ **Post date:** [August 18, 2024, 8:39pm UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/1 "2024-08-18T20:39:05Z")
addGrid.gvpr - a postprocessor that will add a grid to your Graphviz graph. ![unix.Ranks](https://global.discourse-cdn.com/graphviz/original/2X/8/89597d365ed9d0cd89abf40bad5479c625e60aaa.png) Find it [here](https://gist.github.com/steveroush/325b594e0547e2abbc79c5106d8e8db3) It can do horizontal, vertical, or both; edge styles, (multiple) colors, fixed increment or centered on ranks. Mostly a toy, but probably useful on larger graphs. Example command line: ```auto dot myFile.gv | gvpr -a 'size=rank Gcolor=green,purple,red grid=horizontal' -cf addGrid.gvpr |neato -n2 ... ``` Enjoy ---
**Author:** ![Vithanco](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/vithanco/32/292_2.png) [@Vithanco](https://forum.graphviz.org/u/Vithanco)\ **Post date:** [August 26, 2024, 6:30am UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/2 "2024-08-26T06:30:48Z")
Hi Steve, this is pretty impressive and it made me think. I even had a look at the manual: [gvpr | Graphviz](https://graphviz.org/docs/cli/gvpr/) but I don’t think it provided the answer to this question: what is the output of gvpr? I thought it was a tool dot → dot, but these lines aren’t part of the dot language afaik. So, what is the outcome? Or which tool is the output formatter? Cheers, Klaus ---
**Author:** ![steveroush](https://avatars.discourse-cdn.com/v4/letter/s/a9adbd/32.png) [@steveroush](https://forum.graphviz.org/u/steveroush)\ **Post date:** [August 26, 2024, 2:00pm UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/3 "2024-08-26T14:00:53Z")
Simple answer: the output of **gvpr** is the **Graphviz** / **dot** language. The grid lines are a result of adding new nodes around the periphery of the graph and then adding (straight) edges connecting the nodes. More complete answer: **gvpr** is a complete language and could probably be used to write a (very simple) compiler. (Not on my TODO list). Here is a [_lint_](https://forum.graphviz.org/t/a-lint-program-for-graphviz-files/2209/3) program written in **GVPR**. No **dot** output, just text. For an example of the breadth of **gvpr** , here is a [radial layout engine](https://forum.graphviz.org/t/a-radial-graphviz-engine-pre-processor/1271) written in **gvpr**. Legal **dot** input and legal **dot** output. ![radialTest103](https://global.discourse-cdn.com/graphviz/original/2X/d/d6ba6c6cb23e5209bb22c7e5926dd4a32e2f63b2.png) ---
**Author:** ![Vithanco](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/vithanco/32/292_2.png) [@Vithanco](https://forum.graphviz.org/u/Vithanco)\ **Post date:** [October 28, 2024, 8:29am UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/4 "2024-10-28T08:29:25Z")
I needed to come back and read this again. Impressive. Well done! Do you have somewhere a list of “documented” gvpr use cases? I see it here mentioned every now and then. But do you have a systematic list of examples? ---
**Author:** ![steveroush](https://avatars.discourse-cdn.com/v4/letter/s/a9adbd/32.png) [@steveroush](https://forum.graphviz.org/u/steveroush)\ **Post date:** [October 29, 2024, 12:39am UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/5 "2024-10-29T00:39:17Z")
Nope, nothing systematic about any of my efforts. I am slowly working on documenting the more interesting programs, if I can figure out what they do. Note that some are posted [here](https://gist.github.com/steveroush). ---
**Author:** ![somms](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/somms/32/1839_2.png) [@somms](https://forum.graphviz.org/u/somms)\ **Post date:** [February 14, 2025, 6:03pm UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/6 "2025-02-14T18:03:25Z")
Moving the conversation to this thread from [Simulate Y axis and horizontal strips - #5 by somms](https://forum.graphviz.org/t/simulate-y-axis-and-horizontal-strips/2723/5) I get an error that may be related to your code (or most probably to my inexperience) When I try to add any parameter using the -a option, I always get an empty output and a “gvpr: gvpr” message: ```auto $ dot input.dot | gvpr -a 'size=rank' -cf addGrid.gvpr // SIZE start: 72pt delta: 0 // SIZE end: 72pt size: 72 delta: 0 // ARG >size=rank< // type: s gvpr: gvpr ``` The “offending line” is 187 Val=substr(ARGV[i],Indx); After adding some prints to debug, the problem is that Indx value is -3. ---
**Author:** ![somms](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/somms/32/1839_2.png) [@somms](https://forum.graphviz.org/u/somms)\ **Post date:** [February 14, 2025, 6:26pm UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/7 "2025-02-14T18:26:10Z")
BIngo. It seems that there is a bug in my gvpr version (2.48.0) and index returns the value of rindex. I have substituted ```auto Indx=1+index(ARGV[i],"="); ``` by ```auto Indx = length(ARGV[i]) - rindex(ARGV[i], "=") + 1; ``` And it works well now. ---
**Author:** ![scnorth](https://sea2.discourse-cdn.com/graphviz/user_avatar/forum.graphviz.org/scnorth/32/89_2.png) [@scnorth](https://forum.graphviz.org/u/scnorth)\ **Post date:** [February 14, 2025, 6:44pm UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/8 "2025-02-14T18:44:30Z")
Are you saying that gvpr has a mistake in its implementation of index. That is possible. ---
**Author:** ![steveroush](https://avatars.discourse-cdn.com/v4/letter/s/a9adbd/32.png) [@steveroush](https://forum.graphviz.org/u/steveroush)\ **Post date:** [February 14, 2025, 9:57pm UTC](https://forum.graphviz.org/t/add-a-grid-to-your-graphs/2402/9 "2025-02-14T21:57:12Z")
Yep, here are two _closed_ Issues that mention gvpr & index [#2211](https://gitlab.com/graphviz/graphviz/-/issues/2211) [#2138](https://gitlab.com/graphviz/graphviz/-/issues/2138)