Problem with R package installation: sf; system library not found - r

Question

I am trying to install the R package sf. It mentions the system dependencies GDAL, GEOS and PROJ.4. I have installed all of these using
$sudo apt-get install libgdal-dev libgeos-dev libproj-dev proj-bin
However sf still complains that it is missing (something from?) the libraries:
$sudo R CMD INSTALL sf_0.6-3.tar.gz
[...]
configure: pkg-config proj exists, will use it
checking proj_api.h usability... yes
checking proj_api.h presence... yes
checking for proj_api.h... yes
configure: PROJ: 4.9.2
checking for pj_init_plus in -lproj... no
configure: error: libproj not found in standard or given locations.
ERROR: configuration failed for package ‘sf’
The same goes for using the install.packages("sf") command in R. I am using R version 3.5.0 on an Ubuntu 16.04 system, I managed to install the package on another computer with R version 3.4.3 but don't know what I did different to make it work then. Both apt and pkg-config --modversion proj say that the version is higher than needed (4.9.2) and i tried to find some info that could help me resolve the problem using pkg-config or on the internet but couldn't find anything. I did find the following line in /usr/include/proj_api.h (found using sudo apt-file search proj_api.h):
projPJ pj_init_plus(const char *);
which mentions the thing in the check not found, but I don't understand in what way it relates to this.
As a note, I do have two versions of R installed, I also have version 3.2.3 on the computer. Could this be a source of the problem? (I am sure, that the version I am installing the sf package to is 3.5)
EDIT
I have found another R package (proj4) with the libproj dependency and tried to install that one. While it did stop at the same error, this one gave a longer message:
>install.packages("proj4")
[...]
checking proj_api.h usability... yes
checking proj_api.h presence... yes
checking for proj_api.h... yes
checking for pj_init_plus in -lproj... no
configure: error: libproj and/or proj_api.h not found in standard search locations.
*** Install PROJ.4 and if necessary set PKG_CPPFLAGS/PKG_LIBS accordingly.
ERROR: configuration failed for package ‘proj4’
The PKG_CPPFLAGS/PKG_LIBS variables? are not found in R, and echo $PKG_LIBS showed nothing either. Might there be a way I could set these so that the packages can be installed?
I am thankful for any tips or hints as to what causes this.
Peter

Answer 1

I think you may be using older versions of libgdal-dev and you
the following question could be the issue you are seeing
Rgdal installation failed on ubuntu 16.04
sudo add-apt-repository -y ppa:ubuntugis/ubuntugis-unstable
sudo apt update
sudo apt install gdal-bin python-gdal python3-gdal libgdal1-dev