Add plot 'Obsfit (Active Obervations Only)'

[dschoenach]

Useful to have, especially for satellite radiances.

Was requested by Reima in Metcoop.

[ewhelan]

Looks good to me.

1. I presume all well tested.
2. I might request some documentation ...

[ewhelan]

Hi @dschoenach

Thanks for this contribution. I assume all is well-tested and works at your end. Could you look at adding a description of this plot to the documentation. It might inspire others to contribute!

[dschoenach]

Hi @dschoenach

Thanks for this contribution. I assume all is well-tested and works at your end. Could you look at adding a description of this plot to the documentation. It might inspire others to contribute!

Actually not so well tested I am afraid:
It takes quite a bit of time for more cycles. Possibly due to R's slow data.frame format.
The new functions group the raw data by DTG, varname and level and compute for each group the rms and mean of fg and an.

Have to check if that can be speed up somehow.

[dschoenach]

Computation speed looks now good

But I think it needs loading library data.table in init.R

Could you make test @ewhelan

[dschoenach]

It should work by placing data.table in init.R, with the standard install script handling the installation.

Ready to merge from my side.