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Calculating the Weighted Average of Two Graphs

  1. Nov 14, 2011 #1
    i have an excel file containing 2 graphs [R & V], and their x & y coordinates in 4 separate lists [the X coordinates of R, the X coordinates of V, the Y coordinates of R, the Y coordinates of V]

    i need to calculate the X & Y coordinates of a 3rd graph through a weighted formula that takes 55% of the R coordinates into account + 45% of the V coordinates into account

    the tricky part is that R & V start and end at different X coordinates...
    for example R starts at x=0 and ends at x=10
    while V starts at x=5 and ends at x=15

    can anyone help define a better formula for this?
    here is what i have so far:
    X = (Xr+Xv)/2
    Y = (Yr)*0.55 + (Yv)*0.45
    the problem with these equations is they dont take into account the different start and end positions of the two graphs

    thank you for any help in advance! best regards!
     
  2. jcsd
  3. Nov 14, 2011 #2

    LCKurtz

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    Just to clarify what you are asking, would this be the same type of problem:

    Graph A gives high temperature data for Jan 1 thru Jan 20, graph B gives high temperature for Jan 10 through Jan 31. You want a graph for the whole month, weighting the readings differently. Is that similar to what you are wanting to do?
     
  4. Nov 14, 2011 #3
    to clarify:
    imagine graph A starting at Jan 1 [point M] and ending at Jan 20 [point N]
    imagine graph B starting at Jan 10 [point O] and ending at Jan 31 [point P]

    i want to generate a set of points that take on a weighted average of the points from graphs A & B but also starts at point M and ends at point P
     
  5. Nov 14, 2011 #4

    LCKurtz

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    Well, you can't calculate the average of two numbers when you don't have two numbers. The only sensible thing to do is to use the values from graph A and B on the intervals where that is all you have, and average the values for the places where you have two readings. Whether that is acceptable I guess depends on what you are doing.
     
  6. Nov 14, 2011 #5
    i get what your saying in only using values for the common interval between both graphs

    but im supposed to somehow use weighted averages to weight the data points as well as the difference between the intervals. fairly complicated ugh

    thank you btw!!
     
  7. Nov 14, 2011 #6

    LCKurtz

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    I guess I would need more context about what you are doing to see if I would have any other suggestions. At this point it doesn't make much sense to me.
     
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