Introduction | Back to top |
So why develop yet another? Partly because I can, that is, to learn now. But also because any most of the libraries have to be downloaded, so you need to always have the internet, and good access at that. Because any library that is supported by companies like Google grow to be large and complex and easy to use unless you want to do something they haven't intended. Because the documentation is not all that great (like much documentation, it's written by the developers for the developers, and not for the users as much). Because for science purposes (which is what I am pursuing), we don't need fancy bar charts, etc, we just need histograms and scatter plots, whereas other libraries are of course comprehensive, and very useful for other things (like business and administration). And so on. Anyway, the UMD Javascript plotting libraries are pretty easy to use, sort of modeled on the Google Charts, lightweight, and downloadable so you don't need to access it over the internet.
What is usually the case in science is that we need histograms, and scatterplots.
Version | Back to top |
var version = umd_show_version(); alert(version);or
var version = umd_show_version();
console.log("Version ="+version);
Access and Usage | Back to top |
<head> o o o <meta name="apple-mobile-web-app-capable" content="yes" /> <meta name="apple-mobile-web-app-status-bar-style" content="default" /> <script src="plots.js"></script>...or wherever you want to store the plot script.
All plots, whether histograms or scatter plots, are drawn in an HTML5 canvas. So to use the utility, you have to following 1 basic rule: you have to instantiate a canvas in HTML before your javascript. For instance, the following might be what you would do:
<canvas id="mycan"></canvas> <script src="myscript.js"></script>The key thing here is that canvas id. Keep track of it, you will need it to instantiate the plot you want to make.
Inside your javascript, you need to first instantiate, then draw. For example, imagine you want to make a histogram from a 1-dimensional array of numbers representing the ages of a sample population. For example:
var xdata = []; // // then fill the data somehow //Inside your javascript, you instantiate a new histogram with the following arguments:
var histo = new umd_histogram(canvas_id,title,nbins,low_first,upper_last);Then you set up a bunch of options:
var options = {
opt1 : value1,
opt2 : value2,
opt3 : value3
}
And then you make the plot using the following syntax:
histo.plot(xdata,options);
Note that the options are just that - optional, if you don't include them then you get a
default minimal set, so the command
histo.plot(xdata);
is perfectly ok.
So to put it all together,you might do the following:
//
// make and array of ages, and fill it somehow
//
var xdata = [];
//
// "book" a histogram with the following arguments:
// canvas id
// histogram title
// number of bins
// low edge of 1st bin
// upper edge of last bin
//
// so here, "mycan" matches the canvas id in the <canvas> tag, followed by
// the title, and the histogram will have 20 bins between 0 and 80
//
var h1 = new umd_histogram("mycan","Age Distribution Histogram",20,0,80);
var hopt = {
xtitle : "Age",
ytitle : "Number"
};
h1.plot(xdata,hopt);
The utility will make the histogram and display it inside the canvas.
Summary
For histograms, instantiate via:
var h1 = new umd_histo(canvas_id,histogram_title,number_bins,low_first,high_last);
and plot via
h1.plot(data,<options>);
where <options> are optional, described below, and data is a 1-dimensional array of numbers you want to have histogrammed.
For scatter plots, instantiate via:
var s1 = new umd_scatterplot(canvas_id,scatterplot_title);
s1.plot(datax,datay,<options>);
where <options> are optional, described below, and datax and
datay are the x-y pair data, each a 1-dimensional array, for the scatterplot.
Options | Back to top |
| Option | Description | Example | Default |
|---|---|---|---|
| active | active canvas. Allows you to click to on histogram box to read out data points. Also there's a white box in the upper left corner, click to read out all data points. |
active:true | active:false |
| active_div | HTML <div> element. You have to add this to your HTML after you give the canvas, e.g. <canvas id="mycan"> <div id="mydif"> |
"mydiv" | n/a |
| debug | debugging, with output to the console | debug:true | debug:false |
| background | background color | "grey" or "#A5A5A5" | default |
| border | histogram border (drawn in black) | border:true | border:false |
| title | title string | title:"My Title" | default to umd_histogram argument |
| title_font | title font | title_font:"14px arial" | title_font:"#12px Courier" |
| xtitle | horizontal axis title string | xtitle:"Age" | none |
| width | canvas width in pixels | width:500 | width:400 |
| height | canvas height in pixels | height:500 | height:400 |
| show_stats | shows stats on upper right side | show_state:true | show_state:true |
| xgrid | number of grid lines along x-axis | xgrid:5 | xgrid:5 |
| ygrid | number of grid lines along y-axis | ygrid:5 | ygrid:6 |
| ymax | vertical axis max for displaying | ymax:20 | maximum bin content |
| Option | Description | Example | Default |
|---|---|---|---|
| normalize | normalize area under histogram | normalize:1 | not enabled |
| hist_color | color of histogram rectange for displaying | hist_color:"yellow" | hist_color:"#4070d0" |
| r_fract | fraction of bin taken up by histogram rectangle | r_fract:1 | r_fract:0.9 |
| f_labels | 1/fraction of all bins that have a label | f_label:4 | f_label:5 |
| Option | Description | Example | Default |
|---|---|---|---|
| xmin | horizontal min value for displaying | xmin:1 | minimum x value from array |
| xmax | horizontal max value for displaying | xmax:1 | maximum x value from array |
| ymin | vertical min value for displaying | ymin:1 | minimum y value from array |
| nxlabels | number of labels in horizontal interval between xmin and xmax inclusive |
nxlabels:4 | nxlabels:5 |
| point_rad | radius of circle used for points | point_rad:2 | point_rad:3 |
| point_color | color of circle used for points | point_color:"blue" | point_color:"#4070d0" |
| log | plot on log scale | log:true | log:false |
| plot_type | 0=points, 1=line, 2=both | plot_type:1 | plot_type:0 |
Overlay | Back to top |
For both histograms and scatter plots, after you invoke the .plot method, you can then invoke .overlay, and provide new data and options as arguments. For instance, to overlay a function on top of a histogram, you might do something like this:
.
.
.
var h = new umd_histogram("mydif","Title",nbins,xlow,xhigh);
var hdata = [];
var hopts = {
opt1 : value,
opt2 : value,
.
.
.
}
h.plot(h,hopts);
//
// now add data on top
//
var ydata = [];
for (var i=0; i<n; i++) ydata.push(...); // this fills ydata
var overlay_options = {
o_opt1 : value,
o_opt2 : value
.
.
.
}
h.overlay(ydata,overlay_options);
What the code will do is take the ydata values, and assume a 1:1 correspondence with this
histogram bins, and plot the data on top. Note that this is ok, because you've specified the
number of bins, and the bin edges, so you should be able to figure out what bin number goes with
what "ydata[i]" value. The code will overlay 1 point on top of each bin.
For scatter plots, it's much the same thing, only here you give it 2 arrays, x and y, and options, like this:
. . . var x_overlay = []; var y_overlay = []; . // fill x_overlay and y_overlay . s.overlay(x_overlay,y_overlay,overlay_options);For scatter plots, the x_overlay and y_overlay pair do not have to have the same array length or be related to the original scatter plot x/y pair. The code just overlays the plots.
| Option | Description | Example | Default |
|---|---|---|---|
| overlay_type | 0=circle,1=box,2=line,3=custom | overlay_type:1 | overlay_type:0 |
| overlay_circle_radius | for type=0 (circle), radius of circle | overlay_circle_radius:3 | overlay_circle_radius:1 |
| overlay_circle_color | for type=0 (circle), color of circle | overlay_circle_color:"blue" | overlay_circle_color:"red" |
| overlay_box_fraction | for type=1 (rectangle) histograms, box width as fraction of bin | overlay_box_fraction:0.5 | overlay_box_fraction:0.25 |
| overlay_box_width | for type=1 (rectangle) scatter plots, box width in pixels | overlay_box_fraction:0.5 | overlay_box_fraction:0.25 |
| overlay_box_color | for type=1 (rectangle), color of box | overlay_box_color:"green" | overlay_box_color:"blue" |
| overlay_line_width | for type=2 (line), width of line | overlay_line_width:1 | overlay_line_width:2 |
| overlay_line_color | for type=2 (line), color of line | overlay_line_color:"yellow" | overlay_line_color:"blue" |
| overlay_character | for type=3 (custom), the character you want to display | overlay_character:"o" | overlay_character:"*" |
| overlay_character_color | for type=3 (custom), color of character to display | overlay_character_color:"blue" | overlay_character_color:"green" |