Applying pure function to rotate the label in a BoxWhiskerChart

Question

Data is available from here

https://www.ocr.org.uk/Images/400305-large-data-set-lds_1-h630-2018-h640-2018-2019-pre-release-data-mei.xlsx

dat = Import["MEI-B_LDS1.xlsx", {"Sheets", "Data"}];

I have replaced all N/A to Missing[].

BoxWhiskerChart[{Values[#]}, ChartLegends -> Keys[#]] &@ GroupBy[dat[[2 ;;, {3, 11}]], First -> Last]

No problem. Works fine.

But then how to I change the labels so that they are rotated 180 degree under the axis? Like this example

Best I can do is

BoxWhiskerChart[{Values[#]}, ChartLabels -> Placed[Keys[#], Axis]] &@ GroupBy[dat[[2 ;;, {3, 11}]], First -> Last]

Struggling with the rotation due to the use of (nested?) pure functions here.

Answer 1

Use the pure function Rotate[#, 90 Degree] & as the third argument of Placed:

BoxWhiskerChart[{Values[#]}, 
   ChartLabels -> Placed[Keys@#, Axis, Rotate[#, 90 Degree] &]] &@
 GroupBy[dat[[2 ;;, {3, 11}]], First -> Last]