I have phasor information (polar vector data pairs, each with magnitude and angle, representing voltage and current measurements) that I would like to display using Javascript. They should look something like the image linked below (my rep isn't high enough to directly post it) which I stole from Jesse's question about MatPlotLib. I would also like to easily change which phasors are displayed by a simple mechanic like clicking on the legend entry.
See a phasor diagram example here.
While I have inspected several code sets, I have yet to find a chart package that is built to handle polar vectors like this. Is my Google-fu lacking or do I need to create everything from scratch?
I feel like this is a cheap workaround, but here's what I ended up doing:
I used the polar chart from jqWidgets and with the series type set to "column" and the flip property switched to "true." I put the data in an array with 0 entries for each possible angle except for where I wanted the phasor displayed. Each phasor gets a dedicated series so the legend lists them all. It's not perfect and the array is much larger than it really should need to be, but it's passable.
While it's not surprising that no power system display package is publicly available for Javascript, I'm sure one has to be out there for educational sites if nothing else.
Related
I'm trying to find a way to dynamically scale a chart's y-axis so the values are shown in single digits, with a exponential denotation at the top, effectively changing this:
To this:
Note, this works automatically in e.g. Matlab/Matplotlib/etc., but I'm struggling to find a solution with the web plotting frameworks (maybe my search language is wrong)... I know D3.js is not a charting library, but I'd be open to a solution that works with the frontend DC.js or the backend D3.js
Edit based on #Gordon's answer below, I get the following graph using this
chart.yAxis().tickFormat(d3.format('.1e'));
Is it somehow possible to move all of the e+6 to the top? Or do I need to write a custom scaling function and insert a separate text box myself?
In dc.js, the axes are straight from d3-axis.
Access them using chart.xAxis() and chart.yAxis(), and to reduce confusion, do this in a separate statement from the rest of your chart initialization.
You can use axis.tickFormat to control how the tick text is formatted.
You can use d3.format to do automatic formatting. It seems like exponent or SI notation might suit what you're doing, although it's not exactly the same as having the exponent in a separate text element like in your screenshot.
Putting it together, this is pretty close
chart.yAxis().tickFormat(d3.format('.1e'))
The tick formatting question comes up a lot. I wonder where we could put this information so that people don't have to ask.
The problem here is I don't really know the right question to ask, but essentially I want to generate a pattern of ngons that all fit perfectly together, kinda like the picture.
Is there an algorithm or anything that can do this?
FYI I'm attempting this in JavaScript
The algorithm you want is a Voronoi Diagram. The essential description of the algorithm is such:
Generate a list of random points on a plane (or get the points as input from somewhere).
Create a geometric map of n-gons that represent all the space in the plane closest to each point.
The resulting graph will look something like this (stylized and colored):
The look and shape of the n-gons depend on the spacing of the points. You can play with different point distributions or generation methods to get a Voronoi Diagram with particular characteristics. You can also play with the n-gons themselves, for example you can treat the boundaries as fuzzy approximations, blending or leaving gaps between adjacent n-gons:
There are a ton of cool things you can do with a Voronoi Diagram, and pretty much every programming language has libraries that can compute one very quickly. For example, one of the interactive examples for Paper.js is a dynamically generated Voronoi Diagram where one of the points is the location of the cursor. Here's another example where someone uses Voronoi Diagrams as one of the steps for procedural terrain generation. Yet another example is a Voronoi Diagram using the locations of all the airports in the world, which you could use to find the closest airport to any location on the planet.
One such library in Javascript is d3-voronoi, though like I said, there are quite a few libraries out there, not to mention a gazillion tutorial articles on how to implement it yourself should you decide to go that route.
Frustrated that there is no extension to do something I want I am writing my own. One of the key features I need is to be able to display graphs within vs code itself (graph refers to both a curve and nodes-edges).
In order to accomplish this I learnt about webviews, but that seems overkill. All I need is some very basic draw functionalities (straight line, bezier curve, circle, text).
The minimum I need to be able to do is:
I have code that generates a list of values over time. All the extension needs to do is read the generated txt file and plot the evolution of the values over time. Ideally this happens in the sidebar.
Any tips?
Webviews are the way to go. You can do things like this with them:
See also my antlr4-vscode extension repo
I've been struggling the past few days to optimize performance on a D3 map, especially on mobile. I am using SVG transforms for zooming and panning but made the following observation: the overkill comes from path strokes used to fake spacing between countries.
I have uploaded a pair of sample maps for comparison:
http://www.nicksotiriadis.gr/d3/d3-map-1.html
http://www.nicksotiriadis.gr/d3/d3-map-2.html
The only difference between the two maps is the stroke path along the country paths, and the difference in performance is even noticeable on desktop devices - but more obvious on mobile. Removing the path strokes makes mobile performance a breeze..
I tried all kinds of svg stroke shape-rendering options without significant results.
Now to the question. Is there any way to remove a thin border from each country to fake the spacing between countries instead of using a stroke?
If anyone else has a different suggestion I'd love to hear it!
Update: Attaching explanation photo.
What I have drawn is this. The red arrow points to the country joints. When adding a stroke in a color same as the background to the country paths (here depicted in dark grey color) it creates the sense that the countries are seprated - however this adds a serious performance hit on mobile devices. What I am looking for is somehow re-shape the countries paths so that their borderlines are where the blue arrow points, but without having a stroke.
Update 2: People seem not to be able to understand what I am looking for, so I am updating this in order to make the question even clearer.
Let's assume that the original countries paths are shown on the left of this image. What I am looking for is a way that I can somehow 'contract' the paths inwards so that the newly created paths shown in red, leave enough empty space between them that will 'emulate' a stroke between them.
Doing this, will leave no use to having an extra layer of strokes, thus gain performance from only using paths instead of paths+strokes.
Update 2: Hello again, I seem to have found a half-solution to my problem. I managed to extract the topojson to shapefile, edit the shapefile the way I want (used a program named OpenJump), but the conversion takes away all the topojson properties I need - id, country name, so I can't convert back to the original topojson.
Does anyone have any suggestions?
D3 has a thing just for that: topojson.mesh() (see documentation). The idea is that since most countries share borders, there's no need to draw the shared borders twice. If you can draw each border only once, you get as much as 80% reduction in the number of strokes you have to draw. The mesh method does the javascript processing to turn a bunch of closed shapes (countries) into the multiline path of just the borders between them. You can then draw that multiline path into a single <path> object that you position on top of the fills.
The mesh looks like this.
Here's another example.
Finally found the answer. This radically improves d3 map performance!
1) I got my topojson file and extracted to shapefile using mapshaper.org. This gives 3 files: .shp, .shx, .dbf . From what I realized the .dbf file holds all the TopoJSON properties/attributes.
2) Opened the .shp shape file to OpenJUMP http://www.openjump.org/ - Which automatically imports the .dbf file as well.
3) I selected the countries layer and went to Tools > Analysis > Buffer.
4) Checked the Update geometry in source layer box so that the geometry is edited without losing the rest of the attributes/properties and added a negative Fixed Distance -0.1. This shrinked all the country geometries to the result I was looking for.
5) Saved Dataset as ESRI Shapefile
6) Reimported BOTH .shp and .dbf that were produced from OpenJUMP back to mapshaper.org - careful, BOTH files.
7) Exported as TopoJSON. Contains new shape and all original properties/attributes!
The following link has been updated with the new produced map; we have a 'bordered' look without the need of strokes.
http://v7.nicksotiriadis.gr/d3/d3-map-1.html
Compare the performance to this link that has the original shapes + stroke. Please try on mobile to see the performance difference!
http://v7.nicksotiriadis.gr/d3/d3-map-2.html
Also, here is the updated world map TopoJSON file in case someone wants some extra performance! :D
http://v7.nicksotiriadis.gr/d3/js/world-topo-bordered.json
There might be a couple of reasons of this behaviour (on my computer, everything is working fine at the same speed ):
Browser
Which browser do you use ? On Chrome, your exemples are working perfectly.
TopoJson
eg. previous answer.
Animation
You are launching the animation when the page is loading. You might want to add a delay (animation().delay(in ms)). There is also a function in D3: queue(), https://github.com/mbostock/queue which load the data before launching a function.
--
If none of this change your problem, and if you want it to work fine on mobile, you can try to mix D3 and Leaflet (map for mobiles), which is great in term of performance by loading tiles.
One example:
http://bl.ocks.org/zross/6a31f4ef9e778d94c204
Hope it helps
I'd like to implement a population pyramid in dc.js.
The goal is to benefit from all advantages of dc.js in terms of integration of d3 & crossfilter (i.e. my population pyramid would interact with all the other dimensions of my viz. I have already seen pretty good examples in d3 (for instance here: Creating Population Pyramid with D3.js ) put I am looking for a solution within dc.js.
My dataset has columns for each age & sex group.
I was initially thinking of using a "one bar rowchart" for each of those groups, use exactly the same axis scale and bring them together in what could look like a population pyramid.
Though this approach seems like not the right one as I will not be able to have a "one bar row chart" (i.e. I will always get at least 2 bars in my rowchart.
Any hints, ideas, suggestions or examples would be really appreciated.
Thanks!
It might be easier to "simply" write a new graph type to dc. If you install dc.js from git and install grunt, you will be able to add a new pyramid graph in the src source file and get it into your dc.js
It's less scary that it sounds, have a look at existing graphs (rowchart or barchart are probably the closest to start for your own need).
Good luck and probably a good idea to join the dc mailing list, you might want to discuss the idea and get help if you get stuck somewhere