How to calculate winddirection from degrees?-CodePudding

I'm reading (JSON) weatherdata into a small delphi-application. The winddirection is represented by a floatvalue from 0-360. What i want is to calculate this value into 8 directions (N,NE,E,NW,S,SE,W,SW) on the compass and show them on my applicationform as a arrowsymbol. I can use a lot of if..then to solve this, but it would be much cleaner code to just calculate it. My mathematical skills is not what they used to be, so i hope some of you coluld help me? Thanks.

CodePudding user response：

You can use this formula: direction = (int)((windDegrees / 45) 0.5) % 8;

This will give you a value from 0 to 7, representing the 8 compass directions. We start counting at 0.

Heres an super simple example :

var
  windDegrees: float;
  direction: integer;
begin
  windDegrees := 190.0;
  direction := (int)((windDegrees / 45)   0.5) mod 8;
  case direction of
    0: ShowMessage('N');
    1: ShowMessage('NE');
    2: ShowMessage('E');
    3: ShowMessage('SE');
    4: ShowMessage('S');
    5: ShowMessage('SW');
    6: ShowMessage('W');
    7: ShowMessage('NW');
  end;
end;

This will display a message box with the string "S".

You can then use the direction variable to display the appropriate arrow symbol on your application form.

CodePudding user response：

Not deplhi but perhaps something like this?

winds=["N","NE","E","SE","S","SW","W","NW","N"]
wind_={WIND_IN_DEGREES}
index=int(round(wind_/45,0))
print(winds[index])