I have an Vue2 app where users capture mileages for their vehicles. I then plot these values on a linegraph using vue-chartjs:
These values are added as follows:
let chartData = {
labels: [],
datasets: [
{
label: "Total Mileage",
backgroundColor: "#ed3237",
data: [],
},
{
label: "Mileage Increase",
backgroundColor: "#333",
data: [],
},
],
};
...
chartData.labels.push(dateHelper.formatDateShort(hist.dateCreated));
chartData.datasets[0].data.push(hist.vehicleMileage);
chartData.datasets[1].data.push(mileageIncrease);
The problem is, this graph does not paint a very accurate picture as the x-axis values are evenly spaced with each dataset value/label combination, even though the dates might not be (and almost certainly would not be) equal durations from each other.
What I think would make the graph more accurate is if I can add a vertical line for exactly every month and then have the points of the line plotted to be correct in relation to these months. I've recreated this in Excel using the same data:
How do I have a custom x-axis lines and labels like that, but still draw my line with the points being correct in relation to this x-acis?
Related
I simply want a best-fitting ellipse or circle for scatter data I have. I have been able to fit a circle to the data using numerous packages, but then the results are clearly nonsense. Maybe I need to do something weird to get results that work (a) for lat/lon data and (b) with Cartopy projections?
I have the following array of longitude/latitude values:
coords = np.array([-153.1906979 , 62.01707771],
[ 13.05660412, 63.15537447],
[-175.82610203, 67.11698477],
[ -10.31730643, 61.74562855],
[ 168.02402748, 79.60818152],
[ -34.46162907, 65.10894426],
[ -57.20962503, 59.49626998],
[ 113.70202771, 68.22239091],
[ -80.43411993, 55.6654176 ],
[ 93.77252509, 76.19392633],
[-104.10892084, 56.68264351],
[ 66.36158188, 67.59664968],
[-127.75176924, 57.31577071],
[-151.83057714, 61.64142205],
[ 17.44848859, 56.02194986],
[-176.30087703, 66.5955554 ],
[ -5.48747931, 61.95844561],
[ 160.22917767, 66.07650153],
[ -27.93440014, 67.82152994],
[ 137.09393573, 63.71148003],
[ -53.3290508 , 55.79699915],
[ 109.42329666, 75.43090294],
[ -76.59105583, 59.18143738],
[ 89.94733587, 63.50658353],
[-100.54585734, 55.16704225],
[ 66.15810397, 64.64851675],
[-123.65415058, 60.14507524],
[ 41.00262656, 70.67714209],
[-145.66917977, 68.55315102],
[ 18.34306395, 67.62222778])
I plot them on a map as following:
fig = plt.figure(figsize=(20,20))
ax = fig.add_subplot(121,projection=ccrs.NearsidePerspective(central_longitude=0, central_latitude=90,
satellite_height=30785831))
ax.add_feature(cfeature.NaturalEarthFeature('physical', 'ocean', '50m', facecolor='#daf7f7', alpha=0.7, zorder=0))
ax.add_feature(cfeature.NaturalEarthFeature('physical', 'land', '50m', facecolor='#ebc7a4', edgecolor='black', alpha=0.7,zorder=0))
ax.set_global()
grid = ax.gridlines(draw_labels=True)
grid.xlabel_style = {'size': 20, 'color': 'black'}
grid.ylabel_style = {'size': 20, 'color': 'black'}
ax.scatter(coords[0:,0], coords[0:,1], c='red', s=40, zorder=1, transform=PlateCarree())
I get this plot
All I now want to do is fit an ellipse or a circle to this scatter data. Using the solution here: https://stackoverflow.com/a/52877062/17583970, I cannot even try plot anything because the b axis of the ellipse is just a nan. Using skg.nsphere_fit() gave a radius of 433, which is obviously wrong or needs transforming in some way.
Any help would be greatly appreciated.
The coordinates you use really matter in this case. Any fitting will use some sort of distance metric that's being minimized, and the distance in lat/lon coordinates doesn't reflect something in meters or miles at all:
https://en.wikipedia.org/wiki/Geodesics_on_an_ellipsoid
If you're willing to assume that your map projection is a reasonable distance metric you can simply transform the coordinates, and perform the fit on those. I suspect that in this case the fit will be slightly biassed towards the pole (center of the map), making the ellipse a little smaller than it would be when fitted using the actual distance on the earths surface.
Using Cartopy to define the projections of your data and map:
data_proj = ccrs.PlateCarree()
map_proj = ccrs.NearsidePerspective(central_longitude=0, central_latitude=90, satellite_height=30785831)
Those can then be used to convert the coordinates to the map projection:
coords_map = map_proj.transform_points(data_proj, coords[:,0], coords[:,1])[:, :-1]
Fitting (and predicting) an ellipse using Scikit-Image:
from skimage.measure import EllipseModel
model = EllipseModel()
model.estimate(coords_map)
ellipse_coords = model.predict_xy(np.linspace(0, 2*np.pi, 100))
That gives the vertices of the ellipse in the map projection. You could consider converting them back to lat/lon, which would allow you to use ccrs.Geodetic and have Cartopy plot the segments as great circles. But sampling the predicted ellipse in map coordinates might already be fine.
This results in:
fig, ax = plt.subplots(figsize=(6,6), subplot_kw=dict(projection=map_proj), dpi=86, facecolor="w")
ax.add_feature(cfeature.NaturalEarthFeature('physical', 'ocean', '110m', facecolor='#C6EEFF', alpha=1, zorder=0))
ax.add_feature(cfeature.NaturalEarthFeature('physical', 'land', '110m', facecolor='#A2BAA4', edgecolor='none', alpha=1,zorder=0))
ax.set_global()
grid = ax.gridlines(draw_labels=True, lw=0.5, color="k", alpha=0.2)
ax.plot(coords_map[0:,0], coords_map[0:,1], "o", mfc="none", mec='#A70000', mew=1, ms=5, zorder=1, transform=map_proj)
ax.plot(ellipse_coords[:, 0], ellipse_coords[:,1], "-", color="#A70000", transform=map_proj)
Trying to create a chart as show below
Tried to get most of it working fiddle is in
https://jsfiddle.net/BlackLabel/j1pz28y3/
But only axis is the issue. Unable to get multiple axis for different chart and also axis on the left rather than right please help me by pointing to some demo
You need to set yAxis.opposite to false. Your image shows only two axis (first one for the line and flag series, the second one for the column), so here is the example config basing on the image:
yAxis: [{
opposite: false,
height: '60%'
}, {
opposite: false,
top: '65%',
height: '40%',
offset: 0
}],
Demo:
https://jsfiddle.net/BlackLabel/at8Lyod4/
API Reference:
https://api.highcharts.com/highstock/yAxis.opposite
I am using chartjs 2.9.3. I want to have linear scale for x axis for bar plots. It should work just like any linear scale of line plots representing negative, decimal, positive values.
I have managed to create almost similar scale here using this options.
scales: {
xAxes: [
{
type: "time",
time: {
parser: "Y",
unit: "year",
displayFormats: {
year: "Y"
}
},
}
]
},
But it is not working for decimal values, when dataset has negative x values, it is just rounding off to integer and placing the bar at that position.
How can represent decimal values as well?
Chartjs >=3.0.0 has introduced linear scale for bar plots. But this version has some other bugs in it so I am stuck with 2.9.3 version
I don't recommend to change the axis type to time, as this will introduce several other issues given that there are not "fractional times". And adding support for it is not that easy.
The best bet is to create your own labels with a custom function. For example:
const f = () => {
let a = [];
for (let n = -30; n <= 30; n++) {
a.push(n / 100 + "");
}
return a;
};
To generate from -3.00 to +3.00 (zeros representing decimal places). The bigger the numbers 30 and 100 the bigger the "resolution" of your linear scale.
Demo: https://codesandbox.io/s/react-chartjs-2-example-forked-26bbx?file=/src/index.js
I have some info which is in this format (speed, frequency, date). What happens is that I need to plot this chart with speed x frequency, but I want to allow the users to use the navigation filtering by the date, which is not appearing on the chart.
Also, I have some info which is not built dynamically, which is the limits of speed x frequency. This info will be fixed as reference points on the plot. So, when I filter the plot info (not the limits), it must always display these limit plots.
You can have an idea by this chart, the area plots show the limits for the points (speed, frequency). Then, I would add points of speed x frequency (x date), and filter then by date.
Can you guys give me some advice on this?
here is a JSFIDDLE
JSFIDDLE
data: [
[0, 20, here is a date], [10, 20,here is a date],
[50, 39.9994, here is a date], [100,49.7494, here is a date]
],
Guys, notice that every element of the array in the series has 3 elements [a, b, c], suppose the third one (c) is a DATE and not a random number as it is right now. I want to be able to use the commented the navigator code to filter this series by this C element, which doesn't in fact appear on the chart you see, it is a hidden element, just to filter the data.
There will be a little tricky, if you want to have a navigator in the same chart. Navigator works only with datetime data and it must be connected with the axis from the main chart.
So, you have data in that format:
var points = [
[5, 9, Date.UTC(2016, 1, 0)],
[65, 6, Date.UTC(2016, 1, 1)],
...
You need two x axes - one which represents the data and the other which is connected to the navigator. The second axis must be visible to work with the navigator and must be connected with the datetime data.
So now, except two x axes, you need two series - one with the actual data, and the other consists of [date, y] values from the first series. The additional data will be visible in the navigator - note, that in the navigator you cannot use scatter series - so it will be converted to line series - to happen it without errors, your data should be sorted by date.
series: [{
id: 'main-series',
data: points.map(function(point) {
return [point[0], point[1], point[2], point[1]]
}),
showInNavigator: false,
xAxis: 1,
keys: ['x', 'y', 'date', 'holdY'] //holdY is for easier hiding points
}, {
xAxis: 0,
data: points.map(function(point) {
return [point[2], point[1]];
}),
showInNavigator: true,
enableMouseTracking: false,
color: 'transparent',
showInLegend: false
}],
xAxis: [{
minRange: 1000 * 3600 * 24,
type: 'datetime',
tickLength: 0,
tickLength: 0,
labels: {
enabled: false
},
}, {
type: 'linear'
}],
The last thing you need a callback which will hide/show points after the extremes in the navigator are set. Hiding/showing depends on the third point's property which is date. There is no directly API to hide/show specific points (except pie), but it can be achieved by setting point's value to null (that is why I preserved the real y in holdY).
events: {
afterSetExtremes: function(e) {
var points = this.chart.get('main-series').points;
points.forEach(function(point) {
point.update({
y: e.min <= point.date && point.date <= e.max ? point.holdY : null
}, false, false);
});
this.chart.redraw();
}
}
example: https://jsfiddle.net/3wuwdonn/1/
I would consider using a navigator as a separate chart, then you wouldn't need the second x axis and series in the main chart and you wouldn't need to make them look invisible.
example with a navigator only chart here: http://jsfiddle.net/f7Y9p/
If I have a data like this:
data: [0,0,0,0,0,0,0,0,0,0,0,0,0]
this serie starts on the middle but I want what starts really close than the bottom line and not in the middle.Please take a look in this jsfidle http://jsfiddle.net/gh/get/jquery/1.7.2/highslide-software/highcharts.com/tree/master/samples/highcharts/xaxis/tickwidth/ but change data by my example data (data: [0,0,0,0,0,0,0,0,0,0,0,0,0]), I test with min but in this scenario with all values in 0 did not work.
Thanks
I solve with min: 0,minRange: 1 in xAxis
I would do this simply by setting the yAxis min and max.
Example:
http://jsfiddle.net/jlbriggs/bKr74/1/
You can move xAxis down using offset property (offset: Number; The distance in pixels from the plot area to the axis line.):
xAxis: {
tickWidth: 10,
offset: -155
},
See example at jsfiddle