[59] | 1 | ;+ |
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| 2 | ; |
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[101] | 3 | ; @file_comments |
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[238] | 4 | ; find the closest 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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[231] | 7 | ; @categories |
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| 8 | ; Maps |
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[59] | 9 | ; |
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[242] | 10 | ; @param p0lon {in}{required} {type=scalar} |
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| 11 | ; longitudes of point P0. |
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[136] | 12 | ; |
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[242] | 13 | ; @param p0lat {in}{required} {type=scalar} |
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| 14 | ; latitudes of point P0. |
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[136] | 15 | ; |
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[125] | 16 | ; @param neighlon {in}{optional} |
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[136] | 17 | ; |
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[125] | 18 | ; @param neighlat {in}{optional} |
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[59] | 19 | ; |
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[125] | 20 | ; @keyword RADIANS |
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| 21 | ; if set, inputs and angular outputs are in radians, otherwise degrees. |
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[59] | 22 | ; |
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[125] | 23 | ; @keyword DISTANCE |
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| 24 | ; dis, to get back the distances between P0 and the np1 points P1 in the |
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| 25 | ; variable dis. |
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| 26 | ; |
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[238] | 27 | ; @keyword SPHERE |
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| 28 | ; to activate if points are located on a sphere. |
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[125] | 29 | ; |
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[101] | 30 | ; @returns |
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[125] | 31 | ; index giving the P1[index] point that is the closest point of (P0) |
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[59] | 32 | ; |
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[101] | 33 | ; @examples |
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[371] | 34 | ; |
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| 35 | ; IDL> print, neighbor(-105.15,40.02,[-0.07,100,50],[51.30,20,0], $ |
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| 36 | ; distance=dis) |
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[59] | 37 | ; 0 |
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[371] | 38 | ; IDL> print, dis |
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[59] | 39 | ; 105.684 206.125 160.228 |
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| 40 | ; |
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[101] | 41 | ; @history |
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| 42 | ; Sebastien Masson (smasson\@lodyc.jussieu.fr) |
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[59] | 43 | ; October 2003 |
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[118] | 44 | ; |
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[231] | 45 | ; @version |
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| 46 | ; $Id$ |
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[118] | 47 | ; |
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[59] | 48 | ;- |
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[327] | 49 | FUNCTION neighbor, p0lon, p0lat, neighlon, neighlat $ |
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| 50 | , SPHERE=sphere, DISTANCE=distance, RADIANS=radians |
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[59] | 51 | ; |
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[114] | 52 | compile_opt idl2, strictarrsubs |
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| 53 | ; |
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[242] | 54 | ; some checks |
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| 55 | IF n_elements(p0lon) NE 1 THEN ras = report('Sorry p0lon must be a scalar') |
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[59] | 56 | p0lon = p0lon[0] |
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[242] | 57 | IF n_elements(p0lat) NE 1 THEN ras = report('Sorry p0lat must be a scalar') |
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[59] | 58 | p0lat = p0lat[0] |
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[125] | 59 | nneig = n_elements(neighlon) |
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[59] | 60 | IF n_elements(neighlat) NE nneig THEN $ |
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[242] | 61 | ras = report('neighlon and neighlat must have the same number of elements') |
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[59] | 62 | ; distance between P0 and the others points |
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| 63 | IF keyword_set(sphere) THEN BEGIN |
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| 64 | IF sphere NE 1 THEN radius = sphere |
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| 65 | distance = Map_nPoints(p0lon, p0lat, neighlon, neighlat $ |
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| 66 | , radius = radius, radians = radians) |
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[125] | 67 | ENDIF ELSE BEGIN |
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[59] | 68 | distance = (neighlon-p0lon)^2+(neighlat-p0lat)^2 |
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| 69 | IF arg_present(distance) THEN distance = sqrt(distance) |
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| 70 | ENDELSE |
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| 71 | RETURN, where(distance EQ min(distance)) |
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| 72 | END |
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