> I have written v.univar. I am not sure how to calculate statistics

> for lines and areas, does the code below make sense?

Briefly, no. You are calculating weighted means, weighting by line

length or area surface size. I think it would be better to treat each

line or area as a discrete, unweighted, unit unless some reason to the

contrary is given, just like points/sites. It is probably more

important to handle missing data gracefully than weight the means or

other statistics, I think. There may be reasons to weight sometimes,

but most often I see ratios or rates of two variables, rather than of

a single variable and length or area.

I was wondering if some practical examples could be given? The only

thing I could think of is comparing "ground covered in a day" lengths.

This may not be what you were going for, but I have need for something

to help with the "length of border" question. As this is a fractal

problem, the line length is best reported as a ratio (given that the

whole exists at the same resolution).

e.g.

the border with Spain covers x% of Portugal's total borders.

the part of the coastline contained within some vector area represents

x% of the overall coastline.

The integral giving area converges to a real number though, so you could

give mean area + stdev of provinces in a country if you wanted (bad

example..).

In somewhat related matters, I'm planning on activating the C version of

r.univar soon, and for consistency changing r.series to use sample

variance instead of population variance. I think that with raster maps,

you only really have a whole population if you cover the entire planet..

???

This is still missing extended stats (quartiles, median, 10% trimmed

mean), hopefully someone can add that. I might keep the script version

around, renamed r.univar1, until we have that.

Hamish