<p>Here's how to rebuild the plot starting from the <code>gg_both</code> data frame, using <code>ggplot()</code>, with the added ticks:</p>

<pre><code>library(tidyverse)

max_pos &lt;- gg_both %&gt;% filter(col=="+") %&gt;% select(vimp) %&gt;% max
min_neg &lt;- gg_both %&gt;% filter(col=="-") %&gt;% select(vimp) %&gt;% min
vline &lt;- (min_neg - max_pos) / 2 + max_pos

ggplot(gg_both, aes(x=vimp, y=reorder(names, depth), color=col)) + 
  geom_point() +
  scale_x_continuous(breaks=1:22, labels=1:22) +
  geom_abline(slope=1, lty=2, color="red") +
  geom_vline(xintercept = vline, lty=2, color="red") + 
  geom_hline(yintercept = attr(gg_both, "modelsize") + .5, lty=2, color="red")
</code></pre>

<p><a href="https://i.stack.imgur.com/eZihc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/eZihc.png" alt="vimp"></a></p>

<p>Explanation (excerpts from <a href="https://arxiv.org/pdf/1501.07196.pdf" rel="nofollow noreferrer"><code>ggRandomForests: Random Forests for Regression</code></a>) arXiv paper:   </p>

<ul>
<li><p>Colors and diagonal line:</p>

<blockquote>
  <p>Points on the red dashed line are ranked equivalently, points below have higher VIMP, those above have higher minimal depth ranking. Variables are colored by the sign of the VIMP measure.  </p>
</blockquote></li>
<li><p>Vertical line:</p>

<blockquote>
  <p>Vertical dashed line indicates the maximal minimal depth for important variables.  </p>
</blockquote></li>
<li><p>Horizontal line (this isn't mentioned in the paper, but it's in the <a href="https://github.com/ehrlinger/ggRandomForests/blob/master/R/gg_minimal_vimp.R#L151" rel="nofollow noreferrer">source code</a>):</p>

<blockquote>
  <p>...we can put a horizontal line at the MD selection point.</p>
</blockquote></li>
</ul>
How can I adjust axis' scale(or intervals)?
<p>I would like to change axis' scale (or intervals).</p>

<p>On the other hand, I have some trouble with it. </p>

<p>Here's my code what I've implemented as below.</p>

<pre><code>install.packages("randomForestSRC")
install.packages("ggRandomForests")

library(randomForestSRC)
library(ggRandomForests)

data(pbc, package="randomForestSRC") 
pbc.na &lt;- na.omit(pbc)

set.seed(123) 
rsf &lt;- rfsrc(Surv(days, status)~., data=pbc.na,     
             ntree=500, nplist=1, importance=T, proximity=T)

out.vs &lt;- var.select (rsf)
gg_md &lt;- gg_minimal_depth(out.vs)
gg_both &lt;- gg_minimal_vimp(gg_md)
plot(gg_both)
</code></pre>

<p>In that case, the graph can be shown like this.
<a href="https://i.stack.imgur.com/pbLOE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/pbLOE.png" alt="enter image description here"></a></p>

<p>However, What I want to do is that adjusting x-axis scale from 0 to 22 by 1.</p>

<p>So although I've conducted the added code as below, it didn't work.</p>

<pre><code>#### It doest not work.
plot(gg_both)+
  ggplot2::scale_x_continuous(breaks=seq(0, 22, 1))


### It is working but no information about positive $ negative VIMP, dashed lines, etc.
ggplot2::ggplot(gg_both, ggplot2::aes(x=vimp, y=names))+
  ggplot2::geom_point(color="black")+
  ggplot2::scale_x_continuous(breaks=seq(0, 22, 1))
</code></pre>

<p>Please let me know how to do what I want to.</p>

<p>Thanks always.</p>