Read and explore NetCDF files
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Manohar-94 and maasencioh added support to 64 bit offset file (#12)
* added support to 64 bit offset file

* updated the dist files

* chore: remove builded files

use of yarn instead of npm5
Latest commit 32d5e2a Jun 12, 2017

README.md

netcdfjs

NPM version build status Test coverage David deps npm download

Read and explore NetCDF files

Installation

$ npm install netcdfjs

API Documentation

For further information about the grammar you should go to this link.

Example I: NodeJS

const fs = require('fs');
const NetCDFReader = require('netcdfjs');

// http://www.unidata.ucar.edu/software/netcdf/examples/files.html
const data = fs.readFileSync('madis-sao.nc');

var reader = new NetCDFReader(data); // read the header
reader.getDataVariable('wmoId'); // go to offset and read it

Example II: Load from URL (does not require node)

// First load the netcdfjs library as normal : <script src='./dist/netcdfjs.js'></script>
// You could use the oficial CDN: <script src='http://www.lactame.com/lib/netcdfjs/0.3.0/netcdfjs.min.js'></script>

var urlpath =  "http://www.unidata.ucar.edu/software/netcdf/examples/madis-sao.nc"
var reader;

var oReq = new XMLHttpRequest();
oReq.open("GET", urlpath, true);
oReq.responseType = "blob";

oReq.onload = function(oEvent) {
  var blob = oReq.response;
  reader_url = new FileReader();
  
  reader_url.onload = function(e) {
    reader = new netcdfjs(this.result);
  }
      
  reader_url.readAsArrayBuffer(blob);
};
oReq.send(); //start process

reader.getDataVariable('wmoId'); // go to offset and read it

Example III: Client side file upload.

This example creates a file input element and allows the user to select a file from their personal machine.

var reader;
var progress = document.querySelector('.percent');
function abortRead() {  reader.abort(); }

function handleFileSelect(evt) {
  // Reset progress indicator on new file selection.
  progress.style.width = '0%';
  progress.textContent = '0%';

  reader = new FileReader();
  reader.onerror = errorHandler;
  reader.onprogress = updateProgress;
  reader.onabort = function(e) {
    alert('File read cancelled');
  };
  reader.onloadstart = function(e) {
    document.getElementById('progress_bar').className = 'loading';
  };
  reader.onload = function(e) {

    // Ensure that the progress bar displays 100% at the end.
    progress.style.width = '100%';
    progress.textContent = '100%';
    setTimeout("document.getElementById('progress_bar').className='';", 2000);
    //var reader = new NetCDFReader(reader.result);

    //replace reader with NetCDF reader
    reader = new netcdfjs(this.result);
    reader.getDataVariable('wmoId'); // go to offset and read it

   //... your program here  ..//

  }
  reader.readAsArrayBuffer(evt.target.files[0]);
}

// Make input element <input type="file" id="files" name="file" />
var input = document.createElement("input");
input.id='files'
input.type = "file";
input.className = "file"; 
document.body.appendChild(input); // put it into the DOM

// Make a Progress bar <div id="progress_bar"><div class="percent">0%</div></div>
var progress = document.createElement("div");
progress.id='progress_bar';
inner = document.createElement("div");
inner.className = "percent";
inner.id='innerdiv' // set the CSS class
progress.appendChild(inner);
document.body.appendChild(progress); // put it into the DOM

//Start event listener to check if a file has been selected
run = document.getElementById('files').addEventListener('change', handleFileSelect, false);

///Progress bar and other functions 
function errorHandler(evt) {
  switch(evt.target.error.code) {
    case evt.target.error.NOT_FOUND_ERR:
      alert('File Not Found!'); break;
    case evt.target.error.NOT_READABLE_ERR:
      alert('File is not readable');break;
    case evt.target.error.ABORT_ERR: break;
    default: alert('An error occurred reading this file.');
  };
}

function updateProgress(evt) {
  // evt is an ProgressEvent. Updates progress bar
  if (evt.lengthComputable) {
    var percentLoaded = Math.round((evt.loaded / evt.total) * 100);
    // Increase the progress bar length.
    if (percentLoaded < 100) {
      progress.style.width = percentLoaded + '%';
      progress.textContent = percentLoaded + '%';
    }
  }
}

License

MIT