Netcdf 文件多属性,按照时间段导出代码示例
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Netcdf 文件多属性,按照时间段导出代码示例
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由于個人即是java初學者,又是netcdf文件小白,所以為了實現最終效果,可以對一個初始nc文件進行篩選指定變量,并且可以設定時間區間,花得時間比想象的要多,最終實現了效果,代碼示例如下:
@GetMapping("/export")public String varExport(@ModelAttribute FileSaveVars params ) throws IOException, InvalidRangeException { // 0° 設置時間String timeStart = "2018-01-01 00:30:00";String timeEnd = "2018-01-01 00:35:00"; // 1° 設置原始文件路徑+轉存文件路徑String filePath = "/Users/caowei/workspace/jszone/大氣系統/ncdemo/src/main/resources/static/MERRA2_400.tavg1_2d_flx_Nx.20180101.SUB.nc";String savePath = "/Users/caowei/workspace/test.nc"; // 2° 讀取文件NetcdfFile ncFile = NetcdfFile.open(filePath, null); // 3° 設置時間變量Variable timeObject = ncFile.findVariable("time");String timeAt = timeObject.getUnitsString();String regex = "\\d{4}-\\d{2}-\\d{2} \\d{2}:\\d{2}:\\d{2}";Pattern p = Pattern.compile(regex);Matcher matcher = p.matcher(timeAt);if (matcher.find()) {timeAt = matcher.group(0);} // 3-1° 獲取時間差int timeDiff1 = DateHelp.dateDifference(timeAt,timeStart);int timeDiff2 = DateHelp.dateDifference(timeAt,timeEnd); // 3-2° 獲取時間步長Array timeArray = timeObject.read();int timeStep = (int)(timeArray.getFloat(1) - timeArray.getFloat(0)) ;int startIndex = timeDiff1/timeStep;int endIndex = timeDiff2/timeStep;// 4° 構造輸出保存文件NetcdfFileWriter ncWrite = NetcdfFileWriter.createNew(NetcdfFileWriter.Version.netcdf4, savePath); // 4-1° 文件維度for(Dimension dimension : ncFile.getDimensions()){// 對時間特殊處理 為Unlimitedif(dimension.getName().equals("time")){ncWrite.addUnlimitedDimension("time");} else {ncWrite.addDimension(null, dimension.getName(), dimension.getLength());}} // 5° 設置需要轉存的變量List<String> varNames = Arrays.asList("time","lon","lat","QLML");List<Variable> varArray = new ArrayList<>();for(String varName : varNames){Variable varObject = ncFile.findVariable(varName);Variable varVar = ncWrite.addVariable(null, varObject.getName().toString(), varObject.getDataType(),varObject.getDimensionsString());if(varName.equals("time")){List<Attribute> AttrList = varObject.getAttributes();for (Attribute att : AttrList) { // 對單位參數特殊處理if( att.getName().equals("units")) {varVar.addAttribute(new Attribute("units","minutes since "+timeStart));} else {varVar.addAttribute(att);}}}else {varVar.addAll(ncFile.findVariable(varName).getAttributes());}varArray.add(varVar);} // 6° 創建ncWrite.create(); // 7° 變量賦值for(Variable varItem : varArray){int rank= varItem.getRank();String varName = varItem.getName();if(rank == 1){if(varName.equals("time") ) {List<Range> tyxRanges = new ArrayList<>();tyxRanges.add(new Range(null,startIndex,endIndex));Array varData = ncFile.findVariable(varName).read(tyxRanges);ncWrite.write(varItem, varData);} else {Array varData = ncFile.findVariable(varName).read();ncWrite.write(varItem, varData);}}if(rank == 3){int[] shapes = varItem.getShape();int lonSize = shapes[1];int latSize = shapes[2];List<Range> tyxRanges = new ArrayList<>();tyxRanges.add(new Range(null,startIndex,endIndex));tyxRanges.add(new Range(null,0,lonSize-1));tyxRanges.add(new Range(null,0,latSize-1));ncWrite.write(varItem, ncFile.findVariable(varName).read(tyxRanges));}} // 8°關閉保存ncWrite.close();return "OK";}總結
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