[67] | 1 | PRO ncdf_read,filename,info,dinfo,vinfo,gatts,vatts,data |
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| 2 | ; -------- ---- ----- ----- ----- ----- ---- |
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| 3 | ; | | | | | | |
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| 4 | ; general info --' | | | | `-- data |
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| 5 | ; dimension info --------' | | `-------- variable attributes |
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| 6 | ; variable info --------------' `-------------- global attributes |
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| 7 | ; |
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| 8 | ; ================== |
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| 9 | ; read a NetCDF file |
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| 10 | ; ================== |
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| 11 | ; |
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| 12 | ; NB The data is read into a rather nasty combination of structures, arrays, |
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| 13 | ; and pointers, which is, unfortunately, necessary in order to cope with |
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| 14 | ; the full generality of the data format. Here is the sort of syntax you |
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| 15 | ; might use to get at elements of the returned data -- cumbersome because |
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| 16 | ; IDL doesn't support C-type "a->b" shorthand for "(*a).b". |
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| 17 | ; |
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| 18 | ; "INFO.NDIMS" |
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| 19 | ; "INFO.NVARS" |
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| 20 | ; "INFO.NGATTS" |
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| 21 | ; "INFO.RECDIM" |
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| 22 | ; |
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| 23 | ; "DINFO[idim].NAME" |
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| 24 | ; "DINFO[idim].SIZE" |
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| 25 | ; |
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| 26 | ; "VINFO[ivar].NAME" |
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| 27 | ; "VINFO[ivar].NAME" |
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| 28 | ; "VINFO[ivar].DATATYPE" |
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| 29 | ; "VINFO[ivar].NDIMS" |
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| 30 | ; "VINFO[ivar].NATTS" |
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| 31 | ; "VINFO[ivar].DIM[ivdim]" |
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| 32 | ; |
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| 33 | ; "GATTS.NAME" |
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| 34 | ; "GATTS.DATATYPE" |
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| 35 | ; "GATTS.LENGTH" |
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| 36 | ; "*GATTS.VALUES" or maybe "STRING(*GATTS.VALUES)" |
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| 37 | ; |
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| 38 | ; "(*VATTS[ivar])[iatt].NAME" |
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| 39 | ; "(*VATTS[ivar])[iatt].DATATYPE" |
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| 40 | ; "(*VATTS[ivar])[iatt].LENGTH" |
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| 41 | ; "*(*VATTS[ivar])[iatt].VALUES" or maybe |
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| 42 | ; "STRING(*(*VATTS[ivar])[iatt].VALUES)" |
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| 43 | ; |
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| 44 | ; "*DATA[ivar]" or maybe "(*DATA[ivar])[idim1,idim2,idim3,...]" |
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| 45 | ; |
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| 46 | ;---------------------------------------------------------------------- |
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| 47 | |
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| 48 | |
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| 49 | ;; open file |
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| 50 | |
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| 51 | id=ncdf_open(filename) |
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| 52 | |
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| 53 | |
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| 54 | ;; info |
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| 55 | |
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| 56 | info=ncdf_inquire(id) |
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| 57 | |
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| 58 | |
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| 59 | ;; dimension info |
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| 60 | |
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| 61 | dinfo=replicate({name:"",size:0L},info.ndims) |
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| 62 | for idim=0,info.ndims-1 do begin $ |
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| 63 | ncdf_diminq,id,idim,name,size |
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| 64 | dinfo[idim].name=name |
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| 65 | dinfo[idim].size=size |
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| 66 | endfor |
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| 67 | |
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| 68 | |
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| 69 | ;; variable info |
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| 70 | |
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| 71 | vinfo=replicate({ name:"", $ |
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| 72 | datatype:"", $ |
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| 73 | ndims:0l, natts:0l, $ |
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| 74 | dim:lonarr(info.ndims) $ |
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| 75 | },info.nvars) |
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| 76 | |
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| 77 | for ivar=0,info.nvars-1 do begin |
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| 78 | var=ncdf_varinq(id,ivar) |
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| 79 | vinfo[ivar].name=var.name |
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| 80 | vinfo[ivar].datatype=var.datatype |
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| 81 | vinfo[ivar].ndims=var.ndims |
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| 82 | vinfo[ivar].natts=var.natts |
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| 83 | vinfo[ivar].dim=var.dim |
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| 84 | endfor |
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| 85 | |
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| 86 | |
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| 87 | ;; global attributes |
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| 88 | |
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[70] | 89 | if info.ngatts gt 0 then begin |
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| 90 | gatts=replicate({name:'', $ |
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| 91 | datatype:'', $ |
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| 92 | length:0L, $ |
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| 93 | values:ptr_new()}, $ |
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| 94 | info.ngatts) |
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| 95 | for iatt=0,info.ngatts-1 do begin |
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| 96 | name=ncdf_attname(id,iatt,/global) |
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| 97 | gatts[iatt].name=name |
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| 98 | att=ncdf_attinq(id,name,/global) |
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| 99 | gatts[iatt].length=att.length |
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| 100 | gatts[iatt].datatype=att.datatype |
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| 101 | ncdf_attget,id,name,vals,/global |
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| 102 | gatts[iatt].values=ptr_new(vals) |
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| 103 | endfor |
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| 104 | endif else begin |
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| 105 | ;; arbitary scalar value |
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| 106 | ;; an empty list would be sensible but IDL doesn't support it |
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| 107 | gatts=-1 |
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| 108 | endelse |
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[67] | 109 | |
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| 110 | |
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| 111 | |
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| 112 | ;; variable attributes |
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| 113 | |
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| 114 | vatts=replicate(ptr_new(),info.nvars) |
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| 115 | for ivar=0,info.nvars-1 do begin |
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[70] | 116 | if vinfo[ivar].natts gt 0 then begin |
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| 117 | vatts[ivar]=ptr_new(replicate({name:'', $ |
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| 118 | datatype:'', $ |
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| 119 | length:0L, $ |
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| 120 | values:ptr_new()}, $ |
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[67] | 121 | vinfo[ivar].natts)) |
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[70] | 122 | for iatt=0,vinfo[ivar].natts-1 do begin |
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| 123 | name=ncdf_attname(id,ivar,iatt) |
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| 124 | (*vatts[ivar])[iatt].name=name |
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| 125 | att=ncdf_attinq(id,ivar,name) |
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| 126 | (*vatts[ivar])[iatt].length=att.length |
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| 127 | (*vatts[ivar])[iatt].datatype=att.datatype |
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| 128 | ncdf_attget,id,ivar,name,vals |
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| 129 | (*vatts[ivar])[iatt].values=ptr_new(vals) |
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| 130 | endfor |
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| 131 | endif else begin |
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| 132 | vatts[ivar]=ptr_new(-1) |
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| 133 | ;; Pointer to arbitrary scalar -- analogous to case of lack of |
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| 134 | ;; global attributes above. We could put a <NullPointer> here |
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| 135 | ;; instead, but try to be friendlier to code that might try |
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| 136 | ;; to dereference it. |
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| 137 | endelse |
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[67] | 138 | endfor |
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| 139 | |
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| 140 | |
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| 141 | ;; data |
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| 142 | |
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| 143 | data=replicate(ptr_new(),info.nvars) |
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| 144 | for ivar=0,info.nvars-1 do begin |
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| 145 | ncdf_varget,id,ivar,val |
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| 146 | data[ivar]=ptr_new(val) |
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| 147 | endfor |
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| 148 | |
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| 149 | |
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| 150 | end |
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