# Question about graphs on Numbers (Way to just point to data?)

Discussion in 'Mac Apps and Mac App Store' started by Helljumper, May 8, 2011.

1. ### Helljumper macrumors member

Joined:
May 24, 2010
#1
So I have this XY Scatter graph that contains about 15,000 data points. This graph is sinusoidal and oscillates back and forth about 11 times throughout the graph. What I need to do is to get the values at the peaks and valleys of each oscillation. Since there are so many data points, it's going to take too long to look through the data to find the exact maximum and minimum at each peak and valley.

I'm wondering if there's a way I can just like click on the peaks of the graph and have Numbers spit out the value at that point. If not, is there any other way you can think of that would help me accomplish this task more efficiently?

2. ### mysterytramp macrumors 65816

Joined:
Jul 17, 2008
Location:
Maryland
#2
It might be easier to help with the actual data ...

1) You could use the LARGE() and SMALL() functions to find the peaks and valleys.

2) Or you could do this ... calculate an average for all 15,000 datapoints. Create an extra column that is the absolute value of that row's value minus the average. Sort (descending) the data ... The peaks and valleys will be at the top of your spreadsheet.

mt

3. ### ScoobyMcDoo macrumors 65816

Joined:
Nov 26, 2007
Location:
Austin, TX
#3
I have found that trying to use a spreadsheet to analyze wave forms, especially ones with large data sets, is futile. You would be better off using a tool like matlab, octave, or JMP.