[web2py] Is it possible to remove row from rows result created from DB?

[Kenny]

Basically, I get the place data with longitude and latitude, calculate it 
if it's more than 3000 miles, remove that row from Rows. 
I am sure that this is wrong. If I can remove the row from fetch rows, how 
can I add extra columns to the rows for distance between two points?
P.S the result has to be Jsoned.

Here's the code

def tester():
    items = db(db.dine_promotion.place_id==db.place.id).select()

    latitude =float(23.790457)
    longitude =float(-47.602542)
    for row in items:
        if row.place.latitude:
            a=float(row.place.latitude)
            b=float(row.place.longitude)
            dist="%.2f" % calc_distance(latitude,longitude,a,b)
            if  dist > 3000:
                items.remove(row)
    return dict(restaurants = items)

--