Extract Excel Scatter Plot with connected by smooth lines Points

[AmazingTrans]

Hi there,

I have a couple of points, and when i do a scatter plot with connected by smooth line plot, it seems like excel does a bezier splines interpolation. I am wondering am i able to extract the data plots from the data chart?
for example if i have
X - Y
0 - 5
180 - 0
360 - 5

i would like to have all datas of Y from X (0 - 360 degree every degree)

Hope someone know how i can do this.

Thanks!

 

[cyrilbrd]

This would make an inverted bell curve or inverted normal curve right? What would you like to achieve?

 

[AmazingTrans]

cyrilbrd.

Yes that is true. When the chart is plotted by using the excel "scatter plot with connected by smooth line" function, I want to retrieve all the data point in that chart other than the 3 datapoints I specified. I would like the Y position when x is 60 degree, and etc.

 

[cyrilbrd]

have you tried this?
link.

what version of Excel are you using? Excel 2007 allows to see the coordinates of any points by moving the cursor over the chart.

 

[AmazingTrans]

have you tried this?
link.

what version of Excel are you using? Excel 2007 allows to see the coordinates of any points by moving the cursor over the chart.

I'm using excel 2003 only. But i guess i can get a excel 2007. Since excel 2007 is able to read all the points by moving the cursor, does that mean there is a way i can retrieve the co-ordinates using some kind of functions. For example, I am able to provide the x axis values, and i would need the y values from the graph.

 

[cyrilbrd]

Yes maybe 2007 would be a good move, beside 2007 offers a good deal of features that may be worth the upgrade.
And yes, you can retrieve the Y if you know the quadratic equation corresponding to your curve right?

 

[AmazingTrans]

Cybrilbrd,

Unfortunately, it is not a quadratic curve. The points that i gave was just a sample. The graph that i have has about 9 degree or even more up to 15 plus degree in polynomial. And the excel charts uses a bezeir spline to fit the points. So, the question back here is, do you think it is still possible to retrieve these points in any way? for example: if what you said is true, when i put my mouse in any x points it gives y, then there surely is a function where i can say utilize this graph and pull out all the y points.
I need to install 07 but i guess no harm asking for now.

 

[AmazingTrans]

I have just tried to put the 3 points plot on my excel 2010 version. I tried moving my mouse over in between two points, it does not show any other points. Are you sure it shows points that it interpolate?

 

[cyrilbrd]

I have just tried to put the 3 points plot on my excel 2010 version. I tried moving my mouse over in between two points, it does not show any other points. Are you sure it shows points that it interpolate?

2007 only. Check Microsoft Excel forum, this neat trick was removed in 2010... Could be done via VBA I think although samples I found are NOT very satisfactory.

I am not sure but I think Mathematica may offer this. I understand what you are referring to. Read this.

 

[tusharm]

No, you can't get the coordinates of any point on a curve plotted by Excel as part of its smooth curve algorithm. At least not by default. And, Excel 2007 does *not* provide that information.

You can check Brian Murphy's work at xlrotor.com. If anyone has information about how to compute data along the smooth curve used by Excel it's on that site.

You also mentioned you have 9th and 15th order polynomials. I imagine you know your industry better than I but I've never heard of anyone using 9th order (let alone 15th order) polynomials for anything!

Also, the amount of data, at least in the example, is extremely sparse. With those 3 data points, the *only* polynomial equation that can be generated with any surety is the 2nd order polynomial (y = 5/180^2*(x-180)^2. Anything else will be a member of an infinitely large family of functions. And, that is only for polynomials. My instinctive reaction, when I see values like PI and 2*PI is to consider a trig function. And, while I am not doing so for this post, I suspect it is possible to construct a *family* of trig functions to meet your requirements.

All that said, if you have more points and are OK with piecewise linear interpolation, consider the following add-in, which, unfortunately, has not been updated in a while. {grin}
Interactive Chart
http://www.tushar-mehta.com/excel/software/interactive_chart_display/index.html

Hi there,

I have a couple of points, and when i do a scatter plot with connected by smooth line plot, it seems like excel does a bezier splines interpolation. I am wondering am i able to extract the data plots from the data chart?
for example if i have
X - Y
0 - 5
180 - 0
360 - 5

i would like to have all datas of Y from X (0 - 360 degree every degree)

Hope someone know how i can do this.

Thanks!