httr importa o pacote openssl que precisa como requisito do sistema libssl-dev ( sudo apt install libssl-dev )
------------------------- ANTICONF ERROR ---------------------------
Configuration failed because openssl was not found. Try installing:
* deb: libssl-dev (Debian, Ubuntu, etc)
...
O pacote curl precisa do requisito do sistema libcurl4-openssl-dev :
------------------------- ANTICONF ERROR ---------------------------
Configuration failed because libcurl was not found. Try installing:
* deb: libcurl4-openssl-dev (Debian, Ubuntu, etc)
...
Então, para instalar, você precisará executar:
sudo apt-get install libssl-dev
sudo apt-get install libcurl4-openssl-dev
Em seguida, inicie um shell R com sudo R e:
install.packages('httr')
install.packages('git2r')
install.packages('devtools')
library(devtools)
install_github('tpoisot/digitize')

