H3 - Show hexagons all over India - leaflet

I am trying to show the hexagons all over the world, (at least all over India) using H3 on my Leaflet map.
I have tried the below logic but it doesn't work:
Logic:
const boundingBoxIndia = [
[38.11727165830543, 76.37695312500001],
[23.785344805941214, 67.41210937500001],
[6.293458760393985, 77.16796875000001],
[28.51696944040106, 98.525390625],
];
const cellIdsInIndia = h3.polyfill(boundingBoxIndia, 13, true);
const hexagonsInIndia = [];
const hexagonInIndia = cellIdsInIndia?.map((cellId, i) => {
const polygon = h3.h3ToGeoBoundary(cellId, false);
return [polygon];
});
hexagonsInIndia.push(hexagonInIndia);
In render:
<IndiaCells cellGroups={hexagonsInIndia} />
Component
const IndiaCells = (props) => {
if (props.cellGroups?.length) {
return props.cellGroups.map((cells, index) => {
return cells.map(([polygon], groupIndex) => {
return (
<div key={groupIndex}>
<Polygon
positions={polygon}
pathOptions={{...}}
></Polygon>
</div>
);
});
});
} else {
return null;
}
};
I am able to render other hexagons for a smaller sample by the same logic. Also the above code takes a lot of time to load the map but hexagons aren't visible. Looks like size might be an issue here.
Is there any better way to show the H3 hexagon grids all over the map? Something like this:

I think you simply have too many H3 cells for the map to handle. Using your bounding box above, h3.polyfill(boundingBoxIndia, 8, true) yields over 1.5M cells - at resolution 13, you're looking at that number times 7^5, or roughly 25.4 billion cells. I'm guessing that you don't see any cells because the polyfill operation runs out of memory, though I'm somewhat surprised that the page doesn't hang completely.
In general, if you want to render cell boundaries at some fine grain, you need to render only the current viewport (and stop rendering when the expected count gets too high, e.g. when you zoom out). See this h3-viewer project for an example of per-viewport rendering using Leaflet.

Related

Can I set an ag-grid full-width row to have autoHeight?

I am trying to render a set of footnotes at the end of my data set. Each footnote should be a full-width row. On the docs page for row height, it says that you can set an autoHeight property for the column you want to use to set the height. Full-width rows, however, aren't tied to any column, so I don't think there's a place to set that autoHeight property.
For reference, here is my cell renderer, which gets invoked if a flag in the data object is true.
import { Component } from '#angular/core';
import { ICellRendererComp, ICellRendererParams } from '#ag-grid-community/core';
#Component({
template: '',
})
export class FootnoteRendererComponent implements ICellRendererComp {
cellContent: HTMLElement;
init?(params: ICellRendererParams): void {
this.cellContent = document.createElement('div');
this.cellContent.innerHTML = params.data.title;
this.cellContent.setAttribute('class', 'footnote');
}
getGui(): HTMLElement {
return this.cellContent;
}
refresh(): boolean {
return false;
}
}
The footnote (the "title" property above) could be one line or several depending on its length and the browser's window size. There may also be several footnotes. Is there a way to set autoHeight for each footnote row? Thanks for any help!
Not sure of CSS autoHeight can be use, but here is some example for calculating height dynamically. Take a look to getRowHeight function, it's works for any rows (full-width too):
public getRowHeight: (
params: RowHeightParams
) => number | undefined | null = function (params) {
if (params.node && params.node.detail) {
var offset = 80;
var allDetailRowHeight =
params.data.callRecords.length *
params.api.getSizesForCurrentTheme().rowHeight;
var gridSizes = params.api.getSizesForCurrentTheme();
return (
allDetailRowHeight +
((gridSizes && gridSizes.headerHeight) || 0) +
offset
);
}
};
Here is the solution I ended up with, though I like #LennyLip's answer as well. It uses some ideas from Text Wrapping in ag-Grid Column Headers & Cells.
There were two parts to the problem - 1) calculating the height, and 2) knowing when to calculate the height.
1) Calculating the Height
I updated the footnote's Cell Renderer to add an ID to each footnote text node, and used it in the function below.
const footnoteRowHeightSetter = function(params): void {
const footnoteCells = document.querySelectorAll('.footnote .footnote-text');
const footnoteRowNodes = [];
params.api.forEachNode(row => {
if (row.data.dataType === 'footnote') { // Test to see if it's a footnote
footnoteRowNodes.push(row);
}
});
if (footnoteCells.length > 0 && footnoteRowNodes.length > 0) {
footnoteRowNodes.forEach(rowNode => {
const cellId = 'footnote_' + rowNode.data.id;
const cell = _.find(footnoteCells, node => node.id === cellId);
const height = cell.clientHeight;
rowNode.setRowHeight(height);
});
params.api.onRowHeightChanged();
}
};
To summarize, the function gets all HTML nodes in the DOM that are footnote text nodes. It then gets all of the table's row nodes that are footnotes. It goes through those row nodes, matching each up with its DOM text. It uses the clientHeight property of the text node and sets the row node height to that value. Finally, it calls the api.onRowHeightChanged() function to let the table know it should reposition and draw the rows.
Knowing when to calculate the height
When I set the gridOptions.getRowHeight property to the function above, it didn't work. When the function fires, the footnote rows hadn't yet been rendered, so it was unable to get the clientHeight for the text nodes since they didn't exist.
Instead, I triggered the function using these event handlers in gridOptions.
onFirstDataRendered: footnoteRowHeightSetter,
onBodyScrollEnd: footnoteRowHeightSetter,
onGridSizeChanged: footnoteRowHeightSetter,
onFirstDataRendered covers the case where footnotes are on screen when the grid first renders (short table).
onBodyScrollEnd covers the case where footnotes aren't on screen at first but the user scrolls to see them.
onGridSizeChanged covers the case of grid resizing that alters the wrapping and height of the footnote text.
This is what worked for me. I like #LennyLip's answer and looking more into it before I select an answer.

Leaflet clearLayers is freezing browser

I have a function that adds many circle markers to a layerGroup
const renderCatalogQuery = (catalog, catalogLayer) => {
catalogLayer.clearLayers();
catalogLayerControl.removeLayer(catalogLayer);
catalogLayerControl.addOverlay(catalogLayer, catalog.name);
for (let [name,lon,lat] of catalog.currentQuery) {
let coordinates = L.latLng(lat,lon)
let myMarker = L.circle(coordinates, {
radius: catalog.markerSize,
color: catalog.markerColor,
weight: 1})
myMarker.bindTooltip(`${name} (${catalog.name})`)
myMarker.on('click', () => displayObjectInformation(catalog, name));
myMarker.addTo(catalogLayer);
}
}
catalogLayerControl is a control.layers , and catalogLayer is a layerGroup. The first time this run it's no problem. It will populate the layerGroup with circle markers and add the layer group to the layer control. The issue I am having is if the number of circle markers is quite large, the browser freezes up due to the clearLayers() method. It works fine for smaller markers. I can't figure out why adding the markers happens no problem, but removing them doesn't work. Is there a better approach I can take here?
I am guessing clear layers is not the culprit, but adding circles one by one while the Layer Group is still on map is more likely to give performance issue.
Try removing the Layer Group from the map before your loop, then add it back once you are done, so that the heavy computation happens only once.
const renderCatalogQuery = (catalog, catalogLayer) => {
catalogLayer.remove(); // First remove the Layer Group from map
catalogLayer.clearLayers();
for (let [name,lon,lat] of catalog.currentQuery) {
// ...
myMarker.addTo(catalogLayer);
}
catalogLayer.addTo(map); // Finally re-add to map
}

Leaflet js dealing with a lot of markers in a single co-ordinate

I am using leafletjs and leafletjs marker clustering to display where my friends live. The problem is that some of them life in a same house, so the coordinates for multiple markers are the same. Issue occurs when there is more than 50 friends living in the same place.
Is there any way, that the markers could be hidden and when a cluster is clicked it would display a table containing all of the names?
My code for adding markers:
export function markersFromData(map, markers) {
return (data) => {
const markerList = [];
data.map((v) => {
const title = v.name;
const marker = L.marker(new L.LatLng(v.latitude, v.longitude), {
opacity: 0,
});
marker.bindPopup(title);
markerList.push(marker);
return markers.addLayer(marker);
});
map.addLayer(markers);
// eslint-disable-next-line
const group = new L.featureGroup(markerList);
map.fitBounds(group.getBounds());
};
}
Map example
Thank you for your time.
A clean solution would be instead of building one marker per data item (i.e. friend), to first group them by matching position.
Then build 1 marker per position, with metadata reflecting the number of items in that position and list of associated names.
Then in the Leaflet Marker cluster group, use the iconCreateFunction to customize the displayed number to sum these number of friends instead of number of child markers.

How to set the zIndex layer order for geoJson layers?

I would like to have certain layers to be always on top of others, no matter in which order they are added to the map.
I am aware of bringToFront(), but it does not meet my requirements. I would like to set the zIndex dynamically based on properties.
Leaflet has the method setZIndex(), but this apparently does not work for geoJson layers:
https://jsfiddle.net/jw2srhwn/
Any ideas?
Cannot be done for vector geometries.
zIndex is a property of HTMLElements, and vector geometries (lines and polygons) are rendered as SVG elements, or programatically as <canvas> draw calls. Those two methods have no concept of zIndex, so the only thing that works is pushing elements to the top (or bottom) of the SVG group or <canvas> draw sequence.
Also, remind that L.GeoJSON is just a specific type of L.LayerGroup, in your case containing instances of L.Polygon. Furthermore, if you read Leaflet's documentation about the setZIndex() method on L.LayerGroup:
Calls setZIndex on every layer contained in this group, passing the z-index.
So, do L.Polygons have a setZIndex() method? No. So calling that in their containing group does nothing. It will have an effect on any L.GridLayers contained in that group, though.
Coming back to your problem:
I would like to have certain layers to be always on top of others, no matter in which order they are added to the map.
Looks like the thing you're looking for is map panes. Do read the map panes tutorial.
This is one of the reason for the implementation of user defined "panes" in Leaflet 1.0 (compared to versions 0.x).
Create panes: var myPane = map.createPane("myPaneName")
If necessary, set the class / z-index of the pane element: myPane.style.zIndex = 450 (refer to z-index values of built-in panes)
When creating your layers, specify their target pane option: L.rectangle(corners, { pane: "myPaneName" })
When building through the L.geoJSON factory, you can loop through your features with the onEachFeature option to clone your layers with specified target pane.
Demo: https://jsfiddle.net/3v7hd2vx/90/
For peoples who are searching about Z-Index
All path layers (so all except for markers) have no z-index because svg layers have a fix order. The first element is painted first. So the last element is painted on top.
#IvanSanchez described good why zIndex not working.
You can control the order with layer.bringToBack() or layer.bringToFront().
With that code you have more options to control the order of the layers.
L.Path.include({
getZIndex: function() {
var node = this._path;
var index = 0;
while ( (node = node.previousElementSibling) ) {
index++;
}
return index;
},
setZIndex: function(idx) {
var obj1 = this._path;
var parent = obj1.parentNode;
if(parent.childNodes.length < idx){
idx = parent.childNodes.length-1;
}
var obj2 = parent.childNodes[idx];
if(obj2 === undefined || obj2 === null){
return;
}
var next2 = obj2.nextSibling;
if (next2 === obj1) {
parent.insertBefore(obj1, obj2);
} else {
parent.insertBefore(obj2, obj1);
if (next2) {
parent.insertBefore(obj1, next2);
} else {
parent.appendChild(obj1);
}
}
},
oneUp: function(){
this.setZIndex(this.getZIndex()+1)
},
oneDown: function(){
this.setZIndex(this.getZIndex()-1)
}
});
Then you can call
polygon.oneUp()
polygon.oneDown()
polygon.setZIndex(2)
polygon.getZIndex()
And now layergroup.setZIndex(2) are working

How to provide a background color for an entire row in ag grid based on a certain value in a column?

I need to provide a background color for an entire row in ag grid based on a condition in a column. I found no such examples where entire row is colored based on a certain value in a column..
The previous answer is somewhat outdated (although still correct and working) and now we have some more control over the styling of the grid. You could use getRowStyle(params) for this job, just like this:
gridOptions.getRowStyle(params) {
if (params.data.myColumnToCheck === myValueToCheck) {
return {'background-color': 'yellow'}
}
return null;
}
Obviously, myColumnToCheck would be the column you're checking your value against (the same name you input in the id/field property of the colDef object), and myValueToCheck would be the value you want said column to have to make the row all yellow.
I hope this helps others. A very common use case in any table or grid including AG Grid is going to be to set the even/odd background color of the whole row of the entire table in a performant way. ALSO, this needs to still work when SORTING.
ALL OF THESE WAYS OF DOING THIS IN AG-GRID ARE WRONG. Even though they WILL work without sort, they will not update properly when you go to use sorting. This is due to something the ag-grid team refers to in this issue https://github.com/ag-grid/ag-grid-react/issues/77 as initialization time properties.
// Initialization problem
getRowClass = (params) => {
if (params.node.rowIndex % 2 === 0) {
return this.props.classes.rowEven;
}
};
<AgGridReact
getRowClass={this.getRowClass}
>
// Initialization problem
getRowStyle = (params) => {
if (params.node.rowIndex % 2 === 0) {
return this.props.classes.rowEven;
}
};
<AgGridReact
getRowStyle={this.getRowStyle}
>
// Initialization problem
rowClassRules = {
rowEven: 'node.rowIndex % 2 === 0',
}
rowClassRules = {
rowEven: (params) => params.node.rowIndex % 2 === 0,
}
<AgGridReact
rowClassRules={this.rowClassRules}
>
// Trying to change the key so a rerender happens
// Grid also listens to this so an infinite loop is likely
sortChanged = (data) => {
this.setState({ sort: Math.random()})
}
<AgGridReact
key={this.state.sort}
onSortChanged={this.sortChanged}
>
Basically, most stuff in grid is just read once and not again, probably for performance reasons to save rerenders.
You end up with this problem when sorting when doing any of the above:
THE FOLLOWIUNG IS THE RIGHT WAY TO ACHIEVE EVEN ODD COLORING:
The correct way to add even/odd functionality in ag-grid is to apply custom css styles as follows:
You will need to overwrite/use ag variables as mentioned in the docs here:https://www.ag-grid.com/javascript-grid-styling/#customizing-sass-variables
The names of the variables in our case are
.ag-grid-even class name, or the .ag-grid-odd class name. You of course only need one if you just want an alternating color to help with visibility. For our purposes we only needed one.
Here is how this process looked in our repo:
1. Make a custom css file that overwrites/uses some of these ag- class variable names. We call it ag-theme-custom.css (I believe it needs to be a css file).
Note: We also have sass variables so this file just has a comment that this color I am adding in css is the value for our variable $GREY_100 so you don't need that part
You now will get the same result but it will still work when sorting.
Answer 2 is correct, but the syntax used is wrong, and caused me several problems trying to sort it out. Trying to minify the answer 2 code barfed, for example. It did work, but it's not proper syntax as far as I can see.
Note, this can be done inline, or with an external
function. For example an external function.
vm.gridOptions = {
columnDefs: columnDefs,
getRowStyle: getRowStyleScheduled
}
function getRowStyleScheduled(params) {
if (params.selected && params.data.status === 'SCHEDULED') {
return {
'background-color': '#455A64',
'color': '#9AA3A8'
}
} else if (params.data.status === 'SCHEDULED') {
return {
'background-color': '#4CAF50',
'color': '#F4F8F5'
};
}
return null;
};
You can add CSS classes to each row in the following ways:
rowClass: Property to set CSS class for all rows. Provide either a string (class name) or array of strings (array of class names).
getRowClass: Callback to set class for each row individually.
<ag-grid-angular
[rowClass]="rowClass"
[getRowClass]="getRowClass"
/* other grid options ... */>
</ag-grid-angular>
// all rows assigned CSS class 'my-green-class'
this.rowClass = 'my-green-class';
// all even rows assigned 'my-shaded-effect'
this.getRowClass = params => {
if (params.node.rowIndex % 2 === 0) {
return 'my-shaded-effect';
}
};
You can define rules which can be applied to include certain CSS classes via the grid option rowClassRules.
The following snippet shows rowClassRules that use functions and the value from the year column:
<ag-grid-angular
[rowClassRules]="rowClassRules"
/* other grid options ... */>
</ag-grid-angular>
this.rowClassRules = {
// apply green to 2008
'rag-green-outer': function(params) { return params.data.year === 2008; },
// apply amber 2004
'rag-amber-outer': function(params) { return params.data.year === 2004; },
// apply red to 2000
'rag-red-outer': function(params) { return params.data.year === 2000; }
};
You can't change the background color of an entire row in one command. You need to do it through the cellStyle callback setup in the columnDefs. This callback will be called per each cell in the row. You need to change the color of the row by changing the color of all the cells.
See the following column definition
{
headerName: "Street Address", field: "StreetAddress", cellStyle: changeRowColor
}
You need to do this for all your columns.
Here is your changeRowColor function.
function changeRowColor(params) {
if(params.node.data[4] === 100){
return {'background-color': 'yellow'};
}
}
It changes the color of a row if the value of the third cell is 100.
I set different color for even and odd rows you can do it in any way..
$scope.gridOptions.getRowStyle = function getRowStyleScheduled(params){
if(parseInt(params.node.id)%2==0) {
return {'background-color': 'rgb(87, 90, 90)'}
}else {
return {'background-color': 'rgb(74, 72, 72)'}
}
};
If you don't need to set the background color conditionally(based on the row data), it is not recommended to use rowStyle, as written on the row style documentation page:
// set background color on even rows
// again, this looks bad, should be using CSS classes
gridOptions.getRowStyle = function(params) {
if (params.node.rowIndex % 2 === 0) {
return { background: 'red' };
}
}
Instead, you can change the row colors using css:
#import "~ag-grid-community/dist/styles/ag-grid.css";
#import "~ag-grid-community/dist/styles/ag-theme-alpine.css";
#import "~ag-grid-community/dist/styles/ag-theme-balham.css";
#import "~ag-grid-community/src/styles/ag-theme-balham/sass/ag-theme-balham-mixin";
.ag-theme-balham {
#include ag-theme-balham((
// use theme parameters where possible
odd-row-background-color: red
));
}
If you are using AdapTable then the simplest way is to use a Conditional Style and apply it to a whole row.
The advantage of this is that it can be at run-time easily by users also.
https://demo.adaptabletools.com/style/aggridconditionalstyledemo