# Question about nodesep ranksep and minlen attributes in dot layout
**URL:** https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365
**Category:** Help
**Created:** [November 13, 2022, 11:58pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365 "2022-11-13T23:58:51Z")
**Posts on this page:** 8
**Page:** 1
### Author:  [@kasra](https://forum.graphviz.org/u/kasra)
#### Post date: [November 13, 2022, 11:58pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/1 "2022-11-13T23:58:51Z")
Hi,
let’s say we have this graph
```auto
digraph {
graph[rankdir=TB nodesep=0.02 ranksep=0.02]
edge[arrowsize=0 style=invis minlen=1 len=0]
node[shape=rect]
a b c
a->b[constraint=false]
a -> c
}
```
The documentation says for
[ranksep](https://graphviz.org/docs/attrs/ranksep/)
Specifies separation between ranks (type: double | doubleList, default: 0.5 (dot) , 1.0 (twopi) , **minimum: 0.02** )
In dot, sets the desired rank separation, in inches.
**This is the minimum vertical distance between the bottom of the nodes in one rank and the tops of nodes in the next**
[minlen](https://graphviz.org/docs/attrs/minlen/)
Minimum edge length ( **rank difference between head and tai** l) type: int, default: 1, minimum: 0
Based on my comprehension, **my expectation is to have a distance of 0.02inch between a and c.**
But I have this :
Could you explain to me why I have this gap?
Is the edge responsible for something?
Thanks,
---
### Author:  [@smattr](https://forum.graphviz.org/u/smattr)
#### Post date: [November 14, 2022, 3:57pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/2 "2022-11-14T15:57:39Z")
My monthly PSA: the forum supports code blocks with Graphviz syntax highlighting:
````auto
```dot
digraph {
like -> so[with="a label"];
}
```
````
which produces:
```nohighlight
digraph {
like -> so[with="a label"];
}
```
---
### Author:  [@steveroush](https://forum.graphviz.org/u/steveroush)
#### Post date: [November 14, 2022, 5:44pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/3 "2022-11-14T17:44:06Z")
Good question. It seems to be strictly related to rank. So **ranksep** should do the trick.
Removing all references to edges does not change things.
```auto
digraph {
//rankdir=LR
graph[nodesep=0 ranksep=.02]
node[shape=circle]
{rank=source a b}
{rank=sink c}
}
```
Gives:
---
### Author:  [@kasra](https://forum.graphviz.org/u/kasra)
#### Post date: [November 14, 2022, 8:05pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/4 "2022-11-14T20:05:16Z")
I explored the documentation but so far I didn’t find any solution.
I am sure there is a way otherwise It’s really surprising.
Do you think that it’s a bug ? or the documentation is not correct?
I think I am missing something here 🥴
---
### Author:  [@steveroush](https://forum.graphviz.org/u/steveroush)
#### Post date: [November 14, 2022, 8:50pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/5 "2022-11-14T20:50:38Z")
My guess is that it is a bug/feature - working as originally designed but incorrectly documented. The clearest documentation I found is here [http://www.graphviz.org/pdf/dotguide.pdf](http://www.graphviz.org/pdf/dotguide.pdf). Addressing **ranksep** , it says:
> The second deals with rank separation, which is the minimum vertical space between the bottoms of nodes in one rank and the tops of nodes in the next.
Generally, I believe the developers expected users to use **record** and **html** nodes to create nodes that abutted each other
---
### Author:  [@scnorth](https://forum.graphviz.org/u/scnorth)
#### Post date: [November 15, 2022, 5:03pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/6 "2022-11-15T17:03:39Z")
This appears to be a bug. The relevant code is in `set_ycoords`
```
while (--r >= GD_minrank(g)) {
d0 = rank[r + 1].pht2 + rank[r].pht1 + GD_ranksep(g); /* prim node sep */
d1 = rank[r + 1].ht2 + rank[r].ht1 + CL_OFFSET; /* cluster sep */
delta = MAX(d0, d1);
if (rank[r].n > 0) /* this may reflect some problem */
(ND_coord(rank[r].v[0])).y = (ND_coord(rank[r + 1].v[0])).y + delta;
```
Notice that because of the definition of delta from d1, the offset between ranks can never be less than `CL_OFFSET`. I don’t know why we believed this. The subsequent comment about needing a guard to skip potentially empty ranks is a little unsettling but doesn’t seem to be a problem, it’s just conservative coding, I would like to think. I don’t see why one multiple of CL\_OFFSET is necessarily even enough. I don’t see any recursion in set\_ycoords so not sure how nesting of clusters is accounted for. The whole thing seems a little foolish; why not just solve a second linear program for y coords. Our code is too brittle.
---
### Author:  [@kasra](https://forum.graphviz.org/u/kasra)
#### Post date: [November 16, 2022, 2:06pm UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/7 "2022-11-16T14:06:13Z")
Thanks for your investigation.
Should I open an issue in the repo?
---
### Author:  [@mark](https://forum.graphviz.org/u/mark)
#### Post date: [November 17, 2022, 6:57am UTC](https://forum.graphviz.org/t/question-about-nodesep-ranksep-and-minlen-attributes-in-dot-layout/1365/8 "2022-11-17T06:57:41Z")
Good idea