Plot R-Theta [angle (0~360 degrees) and amplitude] chart in Excel

[Guest]

How do you plot an R-Theta chart in Excel, i.e. a circular chart with the
independent axis (angle) in degrees from 0 to 360 degrees and amplitude as
the radial distance from the center point?

 

[Tushar Mehta]

How do you plot an R-Theta chart in Excel, i.e. a circular chart with the
independent axis (angle) in degrees from 0 to 360 degrees and amplitude as
the radial distance from the center point?

You have to convert the data to (x,y) with the formulas x=r*cost(theta) and
y=r*sin(theta) where theta is in radians.

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

 

[Guest]

Thanks, Good suggestion.

You have to convert the data to (x,y) with the formulas x=r*cost(theta) and
y=r*sin(theta) where theta is in radians.

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

 

[Andy Pope]

Hi,

These maybe of interest to you.
http://www.andypope.info/charts/polarplot2.htm
http://www.andypope.info/charts/polarplot.htm

Cheers
Andy

 

[Tushar Mehta]

Hi Andy,

I've shied away from using a Radar plot for parametric plots because I've
always seen it as more like a Line chart turned into a circle rather than a
XY Scatter chart.

But, as you demonstrate, it does have some advantages. There's no need to
specify theta values (though, that can be a disadvantage), and the ability
to create a filled-in plot, something not (easily?) possible with a XY
chart.

The big disadvantage is that whatever one wants to do must be accomplished
in theta = 0 to 2*Pi -- though, I am hesitant to make a claim that you might
decide to prove wrong. {grin}

That precludes something like the butterfly plot given by

x=COS(t)*(EXP(COS(t))-2*COS(4*t)-SIN(t/12)^5)
y=SIN(t)*(EXP(COS(t))-2*COS(4*t)-SIN(t/12)^5)

for 0<= t <= 24*Pi

--
Regards,

Tushar Mehta
www.tushar-mehta.com
Excel, PowerPoint, and VBA add-ins, tutorials
Custom MS Office productivity solutions

 

[Andy Pope]

Hi Tushar,

You are correct, any plot which includes values greater the 2*Pi
requires the use of multiple series.

Cheers
Andy

 

[Guest]

Thanks, Great work. I have already satisfied my need by building a
bare-bones chart using the r*sin(a) and r*cons(a) method. Just wanted to
plot a scatter chart of wind speed vs. compass direction from my new weather
station. I don't know if this will work, but you can try viewing it as a .jpg
picture at ftp://wboyer.net/Polar%20Chart/ .