Hi im tryign to create a zigzag path using Path.js's onMouseDrag function but getting in to a bit of a muddle here is a sketch
and code
var path
var zigzag
var length
var count
var delta=[]
tool.fixedDistance= 20
function onMouseDown(event){
path= new Path()
path.add(event.point)
zigzag= new Path()
}
function onMouseDrag(event){
event.delta += 90
path.add(event.delta)
delta.push(event.delta)
}
function onMouseUp(event){
length= path.segments.length
zigzag= new Path()
zigzag.add(event.point)
console.log(delta)
delta.forEach(( zig , i) => {
zigzag.add(i % 2 == 0 ? zig + 20 : zig - 20)
})
zigzag.selected= true
}
Based on my previous answer, here is a sketch demonstrating a possible way to do it.
let line;
let zigZag;
function onMouseDown(event) {
line = new Path({
segments: [event.point, event.point],
strokeColor: 'black'
});
zigZag = createZigZagFromLine(line);
}
function onMouseDrag(event) {
line.lastSegment.point = event.point;
if (zigZag) {
zigZag.remove();
}
zigZag = createZigZagFromLine(line);
}
function createZigZagFromLine(line) {
const zigZag = new Path({ selected: true });
const count = 20, length = line.length;
for (let i = 0; i <= count; i++) {
const offset = i / count * length;
const normal = i === 0 || i === count
? new Point(0, 0)
: line.getNormalAt(offset) * 30;
const point = line.getPointAt(offset).add(i % 2 == 0 ? normal
: -normal);
zigZag.add(point);
}
return zigZag;
}
I am new to google earth engine and not so familiar with javascript. I want to display the cleared images (B4,B3,B2 bands) of Sentinel 2 by each dates in layers (each layer represent each date). The code is shown as below, but always get error 'no Band 4, constant band'. Can anyone help me to solve this problem? Thanks!
var lakes=table.geometry();
Map.centerObject(lakes, 15);
function maskS2clouds(image) {
var qa = image.select('QA60');
// Bits 10 and 11 are clouds and cirrus, respectively.
var cloudBitMask = 1 << 10;
var cirrusBitMask = 1 << 11;
// Both flags should be set to zero, indicating clear conditions.
var mask = qa.bitwiseAnd(cloudBitMask).eq(0)
.and(qa.bitwiseAnd(cirrusBitMask).eq(0));
return image.updateMask(mask).divide(10000);
}
var start = ee.Date('2015-06-20');
var finish = ee.Date('2018-06-01');
var collection = ee.ImageCollection('COPERNICUS/S2')
.filterDate(start, finish)
.filterBounds(lakes)
.filter(ee.Filter.lt('CLOUDY_PIXEL_PERCENTAGE', 10))
.map(maskS2clouds);
var rgbVis = {
min: 0.0,
max: 0.3,
bands: ['B4', 'B3', 'B2'],
};
function addImage(imageL) { // display each image in collection
var id = imageL.id;
var image = ee.Image(imageL.id);
Map.addLayer(image.select(['B4','B3','B2']).clip(lakes),rgbVis,id)
}
collection.evaluate(function(collection) { // use map on client-side
print(collection.features);
collection.features.map(addImage);
})
How to convert from Hex string to ASCII string in JavaScript?
Ex:
32343630 it will be 2460
function hex2a(hexx) {
var hex = hexx.toString();//force conversion
var str = '';
for (var i = 0; i < hex.length; i += 2)
str += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
return str;
}
hex2a('32343630'); // returns '2460'
Another way to do it (if you use Node.js):
var input = '32343630';
const output = Buffer.from(input, 'hex');
log(input + " -> " + output); // Result: 32343630 -> 2460
For completeness sake the reverse function:
function a2hex(str) {
var arr = [];
for (var i = 0, l = str.length; i < l; i ++) {
var hex = Number(str.charCodeAt(i)).toString(16);
arr.push(hex);
}
return arr.join('');
}
a2hex('2460'); //returns 32343630
You can use this..
var asciiVal = "32343630".match(/.{1,2}/g).map(function(v){
return String.fromCharCode(parseInt(v, 16));
}).join('');
document.write(asciiVal);
** for Hexa to String**
let input = '32343630';
Note : let output = new Buffer(input, 'hex'); // this is deprecated
let buf = Buffer.from(input, "hex");
let data = buf.toString("utf8");
I found a useful function present in web3 library.
var hexString = "0x1231ac"
string strValue = web3.toAscii(hexString)
Update: Newer version of web3 has this function in utils
The functions now resides in utils:
var hexString = "0x1231ac"
string strValue = web3.utils.hexToAscii(hexString)
I've found that the above solution will not work if you have to deal with control characters like 02 (STX) or 03 (ETX), anything under 10 will be read as a single digit and throw off everything after. I ran into this problem trying to parse through serial communications. So, I first took the hex string received and put it in a buffer object then converted the hex string into an array of the strings like so:
buf = Buffer.from(data, 'hex');
l = Buffer.byteLength(buf,'hex');
for (i=0; i<l; i++){
char = buf.toString('hex', i, i+1);
msgArray.push(char);
}
Then .join it
message = msgArray.join('');
then I created a hexToAscii function just like in #Delan Azabani's answer above...
function hexToAscii(str){
hexString = str;
strOut = '';
for (x = 0; x < hexString.length; x += 2) {
strOut += String.fromCharCode(parseInt(hexString.substr(x, 2), 16));
}
return strOut;
}
then called the hexToAscii function on 'message'
message = hexToAscii(message);
This approach also allowed me to iterate through the array and slice into the different parts of the transmission using the control characters so I could then deal with only the part of the data I wanted.
Hope this helps someone else!
console.log(
"68656c6c6f20776f726c6421".match(/.{1,2}/g).reduce((acc,char)=>acc+String.fromCharCode(parseInt(char, 16)),"")
)
An optimized version of the implementation of the reverse function proposed by #michieljoris (according to the comments of #Beterraba and #Mala):
function a2hex(str) {
var hex = '';
for (var i = 0, l = str.length; i < l; i++) {
var hexx = Number(str.charCodeAt(i)).toString(16);
hex += (hexx.length > 1 && hexx || '0' + hexx);
}
return hex;
}
alert(a2hex('2460')); // display 32343630
I use this one, it seems more clear to me as I also receive data with spaces like '30 31 38 30 38 30' and the output is 018080
hexToString(hex: string): string {
return hex.split(' ').map(s => string.fromCharCode(parseInt(s,16))).join('');
}
My problem is to know whether or not a point is contained in a polygon (sets of points) on the same surface.
Simple example in my favorite language DART
Point myPoint = new Point(10, 12);
List<Point> myPolygon = [ // The Polygon, for example is simple rect
new Point(2, 7),
new Point(15,7),
new Point(15, 18),
new Point(2, 18)
];
bool pointIsContainedInPolygon(List Polygon){
// .. data processing ...
}
I need to know what is the function: pointIsContainedInPolygon(myPolygon)
I have resumed the code data in the How can I determine whether a 2D Point is within a Polygon? post in dart, here is the result (tested)
bool pnpoly(Point point, List<Point> polygon){
// Step 1: Cut and detail
int nvert = polygon.length;
List<int> vertx = [];
List<int> verty = [];
for(Point vert in polygon){ // Listing x and y pos of all vertices
vertx.add(vert.x);
verty.add(vert.y);
}
// Step 2: Calcul..
bool c = false;
int j = nvert-1;
for (int i = 0; i < nvert; j = i++){
if( ((verty[i]>point.y) != (verty[j]>point.y)) && (point.x < (vertx[j]-vertx[i]) * (point.y-verty[i]) / (verty[j]-verty[i]) + vertx[i]) ){
c = !c;
}
}
return c;
}
Here is my test
List<Point> myPolygon = [ // classic rectangle
new Point(2,2),
new Point(52,2),
new Point(52,41),
new Point(2,41)
];
Point myPoint = new Point(53,40);
print( pnpoly(myPoint, myPolygon) ); // false
I'm a social science person increasingly getting into web programming for data vis work so apologies if this question is dumb. I'm working on a polymaps implementation to visualize country level data over time. I reads in json temporal data and a geojson world map and spits out a quantile chloropleth map that iterates over monthly entries. The heart of this is a country formating function that binds a colorbrewer class to the country geojson objects (see below). This works find for the animation portion. The problem is that I am using a custom d3 layer that displays the date of the data currently displayed and acts as a mouseover control to stop the animation and choose a date or to choose a date once the animation is through. It does this by creating an blank svg element that uses the d3.scale() function to round mouse input to an integer that matches the index of the month desired. I've front loaded all the other calculations on load so that the only thing that happens at mouse over is the change of svg class (this is basically the same as Tom Carden's wealth of nations implementation on Bostock's d3 page here). Unfortunately, this still overloads the browser pretty quickly. Is there another way to do this that I'm totally missing? I admit im new to geojson so maybe some way to construct an array of classes with in the class attribute of the geojson object? Thanks a ton of any help.
function foo(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
n$(geojson[x].element)
.attr("class", geojson[x].data.formats[local])
.add("svg:title");
}
}
EDIT: I'm adding the full script below.
<meta charset="utf-8">
<script src="scripts/d3.v3.js"></script>
<script src="scripts/polymaps.js"></script>
<script src="scripts/nns.js"></script>
<script>
//Polymaps namespace
var po = org.polymaps;
//Chart dimensions
var margin = {top: 20, right: 20, bottom: 20, left: 20};
var w = 960 - margin.right;
var h = 500 - margin.top - margin.bottom;
// Create the map object, add it to #map div
var map = po.map()
.container(d3.select("#map").append("svg:svg").attr("width", w + margin.left + margin.right).attr("height",h +margin.top + margin.bottom).node())
.center({lat: 28, lon: 0})
.zoom(1.85)
.zoomRange([1.5, 4.5])
.add(po.interact());
// Add the CloudMade image tiles as a base layer…
map.add(po.image()
.url(po.url("http://{S}tile.cloudmade.com"
+ "/1a1b06b230af4efdbb989ea99e9841af" // http://cloudmade.com/register
+ "/20760/256/{Z}/{X}/{Y}.png")
.hosts(["a.", "b.", "c.", ""])));
//Import contribution data
d3.json("assets/contributionsTCC1990-1991.json", function(data){
//find length of json data object and loop over it at interval
var dataLength = Object.keys(data).length;
//Create date key/value array using construtor
function date_array_constructor() {
var dateArray = {};
for(var i = 0; i < dataLength; i++) {
var d = i + 1;
dateArray[d] = data[i].date;
}
return dateArray;
}
var dateArray = date_array_constructor();
// Insert date label/control layer and add SVG elements that take on attributes determined by load function
var labelLayer = d3.select("#map svg").insert("svg:g");
map.add(po.geoJson()
.url("assets/world.json")
.tile(false)
.zoom(3)
.on("load", load));
map.container().setAttribute("class", "Blues");
map.add(po.compass()
.pan("none"));
function find_max(data, dataLength) {
var max = 0;
for(var i in data) {
if(data[i] > max) {
max = data[i] + 1;
}
}
return max;
}
function max_array_constructor(data, dataLength) {
var maxArray = {};
for(var i=0;i<dataLength;i++) {
var d = i+1;
maxArray[d] = find_max(data[i].contributions);
}
return maxArray;
}
var maxArray = max_array_constructor(data, dataLength);
function contribution_array_constructor(data, dataLength, tccName, feature) {
var contributions = {};
//iterate over date entries
for(var i=0;i<dataLength;i++) {
//contribution iterator
contributions[i+1] = 0;
for(x in data[i].contributions){
if(x == tccName) {
contributions[i+1] = data[i].contributions[x];
}
}
}
return contributions;
}
function format_array_constructor(data, dataLength, maxArray, feature) {
var formats = {};
// console.log(feature.data.contributions);
//iterate over date entries
for(var i=0;i<dataLength;i++) {
var percentile = feature.data.contributions[i+1] / maxArray[i+1];
if(percentile != 0){
var v = "q" + ((~~(percentile*7)) + 2) + "-" + 9;
}else{
var v = "countries";
}
formats[i+1] = v;
}
return formats;
}
///////////////////////////////
//load function
///////////////////////////////
function load(e) {
//Bind geojson and json
var geojson = e.features;
console.log(geojson);
geojson.dates = dateArray;
for(var x = 0; x < geojson.length; x++) {
// var tccID = geojson[x].data.id;
var tccName = geojson[x].data.properties.name;
geojson[x].data.contributions = contribution_array_constructor(data, dataLength, tccName, geojson[x]);
geojson[x].data.formats = format_array_constructor(data, dataLength, maxArray, geojson[x]);
}
//Insert date label
var dateLabel = labelLayer.append("text")
.attr("class", "date label")
.attr("text-anchor", "end")
.attr("x", w-670)
.attr("y", h )
.text(dateArray[1]);
//Add interactive overlay for date label
var box = dateLabel.node().getBBox();
var overlay = labelLayer.append("rect")
.attr("class", "overlay")
.attr("x", box.x)
.attr("y", box.y)
.attr("opacity",0)
.attr("width", box.width)
.attr("height", box.height)
.on("mouseover",enable_interaction);
function country_class_constructor(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
n$(geojson[x].element)
.attr("class", geojson[x].data.formats[local])
.add("svg:title");
}
}
function foo(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
n$(geojson[x].element)
.attr("class", geojson[x].data.formats[local])
.add("svg:title");
}
}
//incrementor function
function incrementor(local, geojson, dateArray) {
setTimeout(function() {
//set date label to current iteration
d3.transition(dateLabel).text(dateArray[local]);
//construct country classes
country_class_constructor(local, geojson);
// console.log(geojson);
}, 500*local);
}
///////////////////////////////
//Increment on load
///////////////////////////////
country_class_constructor(1, geojson)
for(var i=1; i< dataLength; i++) {
//Set incrementer as local variable
var local = i+1;
var timer = incrementor(local, geojson, dateArray);
}
///////////////////////////////
//interaction element
///////////////////////////////
function enable_interaction(){
var dateScale = d3.scale.linear()
.domain([1,Object.keys(dateArray).length])
.range([box.x + 10, box.x + box.width - 10])
.clamp(true);
timer = null;
overlay
.on("mouseover", mouse_over)
.on("mouseout",mouse_out)
.on("mousemove",mouse_move)
.on("touchmove",mouse_move);
function mouse_over() {
dateLabel.classed("active", true);
}
function mouse_out() {
dateLabel.classed("active", false);
}
function mouse_move() {
update_map(dateScale.invert(d3.mouse(this)[0]),data);
// displayYear(dateScale.invert(d3.mouse(this)[0]));
}
function update_map(userInput) {
var date = Math.floor(userInput);
d3.transition(dateLabel).text(dateArray[date]);
// console.log(date);
// country_class_constructor(date, geojson);
foo(date, geojson);
}
}
}
});
</script>
Edit 2: I forgot to add the JSON format. See below for two months of data:
[
{"date":"11/90",
"contributions":{
"Algeria":7,
"Argentina":39,
"Australia":41,
"Austria":967,
"Bangladesh":5,
"Belgium":4,
"Brazil":27,
"Canada":1002,
"Chile":7,
"China":5,
"Colombia":12,
"Czech Republic":6,
"Denmark":374,
"Ecuador":21,
"Fiji":719,
"Finland":992,
"France":525,
"Germany":13,
"Ghana":892,
"Hungary":15,
"India":40,
"Indonesia":5,
"Ireland":814,
"Italy":79,
"Jordan":6,
"Kenya":7,
"Malaysia":15,
"Nepal":851,
"Netherlands":15,
"New Zealand":22,
"Nigeria":2,
"Norway":924,
"Poland":165,
"Republic of the Congo":6,
"Russia":35,
"Senegal":4,
"Serbia":17,
"Spain":63,
"Sweden":738,
"Switzerland":5,
"Turkey":2,
"United Kingdom":769,
"United States":33,
"Uruguay":10,
"Venezuela":23,
"Zambia":6
}
},
{"date":"12/90",
"contributions":{
"Algeria":7,
"Argentina":39,
"Australia":41,
"Austria":967,
"Bangladesh":5,
"Belgium":4,
"Brazil":27,
"Canada":1002,
"Chile":7,
"China":5,
"Colombia":12,
"Czech Republic":6,
"Denmark":374,
"Ecuador":21,
"Fiji":719,
"Finland":992,
"France":525,
"Germany":13,
"Ghana":892,
"Hungary":15,
"India":40,
"Indonesia":5,
"Ireland":814,
"Italy":79,
"Jordan":6,
"Kenya":7,
"Malaysia":15,
"Nepal":851,
"Netherlands":15,
"New Zealand":22,
"Nigeria":2,
"Norway":924,
"Poland":165,
"Republic of the Congo":6,
"Russia":35,
"Senegal":4,
"Serbia":17,
"Spain":63,
"Sweden":738,
"Switzerland":5,
"Turkey":2,
"United Kingdom":769,
"United States":33,
"Uruguay":10,
"Venezuela":23,
"Zambia":6
}
}
]
After hours of debugging, it turns out that the nns.js library was causing me problems. Each iteration of the animation was creating a new set of DOM objects which started to max out the browser at 25,000. The solution was to use nss to create the initial state and then using the following function to change the class of each svg element.
function country_class_constructor(local, geojson){
for(var x=0;x<geojson.length;x++){
var n = geojson[x].data.properties.name;
element = document.getElementById(n);
element.className["animVal"] = geojson[x].data.formats[local];
element.className["baseVal"] = geojson[x].data.formats[local];
}