Ab initio and From scratch

Ab initio adverb - At the beginning.

From scratch and ab initio are semantically related. in from the beginning topic. In some cases you can use "From scratch" instead the phrase "Ab initio" as an adverb or an adjective. informal substitute

From scratch adverb - From the beginning, especially without relying on resources or other advantages.

Ab initio and from scratch are semantically related. You can use "Ab initio" instead an adverb phrase "From scratch".