The phrase "already understood from" is correct and usable in written English.
It can be used when referring to information or concepts that have been previously comprehended or inferred from a source.
Example: "The conclusions drawn in this report are already understood from the data presented in the previous section."
Alternatives: "previously inferred from" or "already gathered from".
I had already understood from the response to my own book, Somewhere Towards the End, that the taboo on the subject of death, so heavy in my youth, was evaporating, and this was a striking example of how true this is.
Generally, in his mind Megalosaurus resembled a gigantic lizard, but Buckland already understood from the form of the thighbone head that the legs were not so much sprawling as held rather upright.
By giving users total flexibility about how the applications looked and worked, it could be said that Podio didn't give users an already understood point from which to start with.
This sped up development as employees already understood these building blocks, and fewer tools had to be made from scratch.
She saw that they already understood that.
She already understood all about the workings of the mechanism.
We already understood the environment.
Some functions of DNA methylation within Nasonia are already understood.
Someone may need help with something you already understood.
In places like Orange County and San Francisco where smartphone ownership is prevalent, I can see myself as a physician who can use a tablet or smartphone without having to explain the 2-dimensionality, or the limitations of the device because my patient will likely already understand how to translate information from the screen into "real life".
The surveillance protocols in Taiwan remained essentially the same throughout the data period since, by the time the data were collected, clinical characteristics of the pH1N1 infection had already been well understood from the spring outbreaks around the world.
