1 | ;+ |
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2 | ; |
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3 | ; @file_comments |
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4 | ; interpolate data from a "regular/rectangular grid" to any grid. |
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5 | ; |
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6 | ; 2 methods available: bilinear and imoms3 |
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7 | ; |
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8 | ; A "regular/rectangular grid" is defined as a grid for which |
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9 | ; |
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10 | ; Each longitude lines have the same latitude and each latitude columns |
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11 | ; have the same longitude. |
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12 | ; |
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13 | ; @categories |
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14 | ; Interpolation |
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15 | ; |
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16 | ; @param method {in}{required}{type=string} |
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17 | ; the interpolation method. |
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18 | ; must be 'bilinear' or 'imoms3' |
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19 | ; |
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20 | ; @param datain {in}{required}{type=2d array} |
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21 | ; the input data to interpolate |
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22 | ; |
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23 | ; @param lonin {in}{required}{type=1d or 2d array} |
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24 | ; the longitude of the input data |
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25 | ; |
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26 | ; @param latin {in}{required}{type=1d or 2d array} |
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27 | ; the latitude of the input data |
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28 | ; |
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29 | ; @param lonout {in}{required}{type=1d or 2d array} |
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30 | ; the longitude of the output data |
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31 | ; |
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32 | ; @param latout {in}{required}{type=1d or 2d array} |
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33 | ; the latitude of the output data |
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34 | ; |
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35 | ; @keyword WEIG {type=2d array or variable name} |
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36 | ; (see ADDR) |
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37 | ; |
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38 | ; @keyword ADDR {type=2d array or variable name} |
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39 | ; 1) at the first call of fromreg: |
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40 | ; This keyword can be set to a named variable (undefined or equal to 0) into which the |
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41 | ; addresses used to perform the interpolation will be copied when the current routine exits. |
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42 | ; 2) Next, once this keyword is set to a defined 2d array, it is used to bypass the computation |
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43 | ; of the weights and addresses used to perform the interpolation. In this case, fromreg simply |
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44 | ; compute the interpolated field as: |
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45 | ; dataout = total(weig*datain[addr], 1) |
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46 | ; dataout = reform(dataout, jpio, jpjo, /over) |
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47 | ; |
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48 | ; In that case, method, lonin, latin, are not used (but are necessary). |
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49 | ; lonout, latout are used only to know the output domain size |
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50 | ; |
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51 | ; @keyword NONORTHERNLINE |
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52 | ; activate if you don't want to take into account the northern line |
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53 | ; of the input data when performing the interpolation. |
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54 | ; |
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55 | ; @keyword NOSOUTHERNLINE |
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56 | ; activate if you don't want to take into account the southern line |
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57 | ; of the input data when performing the interpolation. |
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58 | ; |
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59 | ; @keyword |
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60 | ; _EXTRA to be able to call fromreg with _extra keyword |
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61 | ; |
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62 | ; @returns |
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63 | ; 2D array the interpolated data |
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64 | ; |
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65 | ; @restrictions |
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66 | ; We supposed the data are located on a sphere, with a periodicity along the |
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67 | ; longitude. |
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68 | ; |
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69 | ; @examples |
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70 | ; |
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71 | ; To interpolate 1 field: |
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72 | ; |
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73 | ; IDL> topa = fromreg('bilinear', tncep, xncep, yncep, glamt, gphit) |
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74 | ; |
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75 | ; or if you have several fields to interpolate from the same source and target grids |
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76 | ; |
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77 | ; 1) get back the weights and addresses in variables a and b |
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78 | ; (that must be undefined or equal to 0 before calling fromreg |
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79 | ; |
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80 | ; IDL> t1opa = fromreg('bilinear', t1ncep, xncep, yncep, glamt, gphit, WEIG = a, ADDR = b) |
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81 | ; IDL> help, a, b |
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82 | ; |
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83 | ; 2) use a and b that are now defined to bypass the computation of the weights and addresses |
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84 | ; and speed-up the computation! |
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85 | ; |
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86 | ; IDL> t2opa = fromreg('bilinear', t2ncep, xncep, yncep, glamt, gphit, WEIG = a, ADDR = b) |
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87 | ; |
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88 | ; @history |
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89 | ; November 2005: Sebastien Masson (smasson\@lodyc.jussieu.fr) |
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90 | ; |
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91 | ; @version |
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92 | ; $Id$ |
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93 | ; |
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94 | ;- |
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95 | FUNCTION fromreg, method, datain, lonin, latin, lonout, latout $ |
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96 | , WEIG=weig, ADDR=addr $ |
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97 | , NONORTHERNLINE=nonorthernline $ |
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98 | , NOSOUTHERNLINE=nosouthernline, _EXTRA=ex |
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99 | ; |
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100 | compile_opt idl2, strictarrsubs |
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101 | ; |
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102 | ;--------------- |
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103 | ; atmospheric grid parameters |
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104 | ;--------------- |
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105 | alon = lonin |
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106 | alat = latin |
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107 | get_gridparams, alon, alat, jpia, jpja, 1, /double |
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108 | ;--------------- |
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109 | ; Oceanic grid parameters |
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110 | ;--------------- |
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111 | olon = lonout |
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112 | olat = latout |
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113 | get_gridparams, olon, olat, jpio, jpjo, 2, /double |
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114 | ;--------------- |
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115 | ; Compute weight and address |
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116 | ;--------------- |
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117 | IF NOT (keyword_set(weig) AND keyword_set(addr)) THEN BEGIN |
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118 | CASE method OF |
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119 | 'bilinear':compute_fromreg_bilinear_weigaddr, alon, alat, olon, olat, weig, addr, NONORTHERNLINE = nonorthernline, NOSOUTHERNLINE = nosouthernline |
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120 | 'imoms3': compute_fromreg_imoms3_weigaddr, alon, alat, olon, olat, weig, addr, NONORTHERNLINE = nonorthernline, NOSOUTHERNLINE = nosouthernline |
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121 | ELSE:BEGIN |
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122 | ras = report(' unknown interpolation method... we stop') |
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123 | stop |
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124 | ENDELSE |
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125 | ENDCASE |
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126 | ENDIF |
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127 | ; |
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128 | ;--------------- |
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129 | ; do the interpolation |
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130 | ;--------------- |
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131 | intype = size(datain, /type) |
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132 | if intype LE 3 THEN dataout = total(weig*float(datain[addr]), 1) $ |
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133 | ELSE dataout = total(weig* datain[addr] , 1) |
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134 | dataout = reform(dataout, jpio, jpjo, /over) |
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135 | IF intype LE 3 THEN dataout = round(temporary(dataout)) |
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136 | ; |
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137 | RETURN, dataout |
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138 | END |
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