[R] Digitizing the Plot

[Greg Snow]

I don't know of anything that does the automated process like the example software you link to, but here is one procedure that you can use to "do it by hand".

1. Brind the graph into R and plot it (as an image) using rimage or EBImage (or other) packages.

2. use the locator function to find the coordinates (under the current user coord system) of 2 points that you know the coordinates of (in the scale of the graph, desired coord system).

3. Use the updateusr function from the TeachingDemos package to convert the coordinates to match the axes (using the points from the previous step).

4. Use the locator function and click on the points/curve in the graph.  The result will be an approximation to the data of interest (you may want to round or do other clean-up, or just use as is).

Hope this helps,

-- 
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at imail.org
801.408.8111


> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-
> project.org] On Behalf Of Shubha Vishwanath Karanth
> Sent: Thursday, April 16, 2009 9:44 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] Digitizing the Plot
> 
> Hi R,
> 
> 
> 
> Wanted to check if there are any packages available for getting the
> (x,y) data points of a graph or a plot, which is in the image format.
> Say, the plot could be a published report, and I want to get the points
> of the curve plotted. (I am speaking something related the subject
> discussed in http://www.uniphiz.com/digitizing.htm)
> 
> 
> 
> 
> 
> Thanks,
> 
> Shubha
> 
> 
> 
> 
> 
> This e-mail may contain confidential and/or privileged
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> 
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