I am faced with the following issue. I got a raster map showing the position and extent of land parcels within a 35 sq Km area. The number of parcels is about 200. In anticipation of the following step, which would be to digitize the parcels and perform further analyses, I wish to select a sample that is random spatially speaking. What would be a viable strategy to achieve that? If the parcels were already digitized, it would be easy for me to take a random sample from the attribute table. But my situation is different, since what I have right now is just a raster map showing parcels position and extent. An idea that I had (but which I am not sure about) is to generate x random points in ArcMap, buffering them (say, 1 km buffer), and select the parcels which for example fall inside the buffer. But I wonder if this could be considered a random sample...


You cannot select something that does not exist.

The fastest workaround is to create random points on the extent of your raster map. However, I warn you that the probability to select a parcel will then be proportionnal to the size of the parcel, and you don't have full control on the final number of selected parcels because more than one point can fall in the same parcel.

The second workaround requires a preliminary step, but with 200 parcel it won't take you too much time: Manually draw one point in the center of each parcel (one click per parcel --> around 30 min all included). Then you can randomly select your points.

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