[59] | 1 | ;+ |
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| 2 | ; |
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[101] | 3 | ; @file_comments |
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| 4 | ;find the closetest point of (P0) within a list of np1 points |
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| 5 | ;P1 Which can be on a sphere |
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[59] | 6 | ; |
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[101] | 7 | ; @categories Maps |
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[59] | 8 | ; |
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[101] | 9 | ; @examples |
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| 10 | ; IDL> Result = neighbor(lon0, lat0, lon1, lat1) |
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[59] | 11 | ; |
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[118] | 12 | ; @param p0lon {in}{required} scalar. longitudes of point P0. |
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| 13 | ; @param p0lat {in}{required} scalar. latitudes of point P0. |
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| 14 | ; @param neighlon {in}{optional} |
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| 15 | ; @param neighlat {in}{optional} |
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[59] | 16 | ; |
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[118] | 17 | ; @keyword RADIANS if set, inputs and angular outputs are in radians, otherwise |
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[101] | 18 | ;degrees. |
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[118] | 19 | ; @keyword DISTANCE dis, to get back the distances between P0 and the np1 |
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[59] | 20 | ; points P1 in the variable dis. |
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[118] | 21 | ; @keyword /SPHERE to activate if points are located on a sphere. |
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[59] | 22 | ; |
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[101] | 23 | ; @returns |
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[118] | 24 | ; index giving the P1[index] point that is the closest point of (P0) |
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[59] | 25 | ; |
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[101] | 26 | ; @examples |
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[59] | 27 | ; IDL> print, neighbor(-105.15,40.02,[-0.07,100,50],[51.30,20,0], $ |
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| 28 | ; distance=dis) |
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| 29 | ; 0 |
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| 30 | ; IDL> print, dis |
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| 31 | ; 105.684 206.125 160.228 |
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| 32 | ; |
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[101] | 33 | ; @history |
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| 34 | ; Sebastien Masson (smasson\@lodyc.jussieu.fr) |
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[59] | 35 | ; October 2003 |
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[118] | 36 | ; |
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| 37 | ; @version $Id$ |
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| 38 | ; |
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[59] | 39 | ;- |
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| 40 | FUNCTION neighbor, p0lon, p0lat, neighlon, neighlat, sphere = sphere, distance = distance, radians = radians |
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| 41 | ; |
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[114] | 42 | compile_opt idl2, strictarrsubs |
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| 43 | ; |
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[59] | 44 | ; somme checks |
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| 45 | IF n_elements(p0lon) NE 1 THEN MESSAGE, 'Sorry p0lon must be a scalar' |
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| 46 | p0lon = p0lon[0] |
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| 47 | IF n_elements(p0lat) NE 1 THEN MESSAGE, 'Sorry p0lat must be a scalar' |
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| 48 | p0lat = p0lat[0] |
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| 49 | nneig = n_elements(neighlon) |
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| 50 | IF n_elements(neighlat) NE nneig THEN $ |
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| 51 | MESSAGE, 'neighlon and neighlat must have the same number of elements' |
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| 52 | ; distance between P0 and the others points |
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| 53 | IF keyword_set(sphere) THEN BEGIN |
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| 54 | IF sphere NE 1 THEN radius = sphere |
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| 55 | distance = Map_nPoints(p0lon, p0lat, neighlon, neighlat $ |
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| 56 | , radius = radius, radians = radians) |
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| 57 | ENDIF ELSE BEGIN |
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| 58 | distance = (neighlon-p0lon)^2+(neighlat-p0lat)^2 |
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| 59 | IF arg_present(distance) THEN distance = sqrt(distance) |
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| 60 | ENDELSE |
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| 61 | RETURN, where(distance EQ min(distance)) |
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| 62 | END |
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