Installing "pcalg" on RStudio

Dear community,

I’m new to DigitalOcean and still lack experience. I set up a Droplet with RStudio on Ubuntu 18.04. To run my code, I need to install the “pcalg” package. However, I always get the following error messsage. Does anyone have an idea how to fix this? Your help would be much appreciated.

> install.packages("pcalg")
Installing package into ‘/home/paul/R/x86_64-pc-linux-gnu-library/3.6’
(as ‘lib’ is unspecified)
Warning in install.packages :
  dependencies ‘graph’, ‘RBGL’ are not available
also installing the dependencies ‘V8’, ‘dagitty’

trying URL 'https://cloud.r-project.org/src/contrib/V8_2.3.tar.gz'
Content type 'application/x-gzip' length 304765 bytes (297 KB)
==================================================
downloaded 297 KB

trying URL 'https://cloud.r-project.org/src/contrib/dagitty_0.2-2.tar.gz'
Content type 'application/x-gzip' length 168082 bytes (164 KB)
==================================================
downloaded 164 KB

trying URL 'https://cloud.r-project.org/src/contrib/pcalg_2.6-2.tar.gz'
Content type 'application/x-gzip' length 4859003 bytes (4.6 MB)
==================================================
downloaded 4.6 MB

* installing *source* package ‘V8’ ...
** package ‘V8’ successfully unpacked and MD5 sums checked
** using staged installation
Using PKG_CFLAGS=-I/usr/include/v8 -I/usr/include/v8-3.14
Using PKG_LIBS=-lv8 -lv8_libplatform
------------------------- ANTICONF ERROR ---------------------------
Configuration failed because  was not found. Try installing:
 * deb: libv8-dev or libnode-dev (Debian / Ubuntu)
 * rpm: v8-devel (Fedora, EPEL)
 * brew: v8 (OSX)
 * csw: libv8_dev (Solaris)
To use a custom libv8, set INCLUDE_DIR and LIB_DIR manually via:
R CMD INSTALL --configure-vars='INCLUDE_DIR=... LIB_DIR=...'
--------------------------------------------------------------------
ERROR: configuration failed for package ‘V8’
* removing ‘/home/paul/R/x86_64-pc-linux-gnu-library/3.6/V8’
Warning in install.packages :
  installation of package ‘V8’ had non-zero exit status
ERROR: dependency ‘V8’ is not available for package ‘dagitty’
* removing ‘/home/paul/R/x86_64-pc-linux-gnu-library/3.6/dagitty’
Warning in install.packages :
  installation of package ‘dagitty’ had non-zero exit status
ERROR: dependencies ‘graph’, ‘RBGL’, ‘dagitty’ are not available for package ‘pcalg’
* removing ‘/home/paul/R/x86_64-pc-linux-gnu-library/3.6/pcalg’
Warning in install.packages :
  installation of package ‘pcalg’ had non-zero exit status

The downloaded source packages are in
	‘/tmp/RtmpQLGKab/downloaded_packages’