问题
I have data that looks like this:
Risk Return
9.2 6.5
7.8 3.4
6.4 5.2
.
.
.
.
10.2 6.4
I created a scatter plot that looks like this:
How can I get just the outer edge of the curve? I'd like it to look like this:
回答1:
Maybe pick off the co-ordinates for points that are nearest to the upper boundary, plot just those co-ordinates as a separate series and add a suitable trend line. Or create the envelope values from the formula shown by plotting the selection with Display Equation on chart. Simplified example:
回答2:
Let say your Risk is in column A rows 2-100, and Return is column B rows 2-100.
Create a column C with this formula (its an array formula so use Ctrl-Shift-Enter): =MAX(IF($A$2:$A$100<=A2,$B$2:$B$100))=B2
Copy down to all of column C. This formula is saying get the max return, of all points with the same or lower risk than this point. If that return is equal to this points return then TRUE.
Now create columns D and E and with formulas like: =IF(C2,A2,0) =IF(C2,B2,0)
This will 0 out the points that are not part of the frontier, you can then plot these points.
来源：https://stackoverflow.com/questions/25331416/how-do-i-plot-just-the-outer-edge-of-a-curve-in-excel