Flot Reference
--------------

Consider a call to the plot function:

   var plot = $.plot(placeholder, data, options)

The placeholder is a jQuery object or DOM element or jQuery expression
that the plot will be put into. This placeholder needs to have its
width and height set as explained in the README (go read that now if
you haven't, it's short). The plot will modify some properties of the
placeholder so it's recommended you simply pass in a div that you
don't use for anything else. Make sure you check any fancy styling
you apply to the div, e.g. background images have been reported to be a
problem on IE 7.

The format of the data is documented below, as is the available
options. The "plot" object returned has some methods you can call.
These are documented separately below.

Note that in general Flot gives no guarantees if you change any of the
objects you pass in to the plot function or get out of it since
they're not necessarily deep-copied.


Data Format
-----------

The data is an array of data series:

  [ series1, series2, ... ]

A series can either be raw data or an object with properties. The raw
data format is an array of points:

  [ [x1, y1], [x2, y2], ... ]

E.g.

  [ [1, 3], [2, 14.01], [3.5, 3.14] ]

Note that to simplify the internal logic in Flot both the x and y
values must be numbers (even if specifying time series, see below for
how to do this). This is a common problem because you might retrieve
data from the database and serialize them directly to JSON without
noticing the wrong type. If you're getting mysterious errors, double
check that you're inputting numbers and not strings.

If a null is specified as a point or if one of the coordinates is null
or couldn't be converted to a number, the point is ignored when
drawing. As a special case, a null value for lines is interpreted as a
line segment end, i.e. the points before and after the null value are
not connected.

Lines and points take two coordinates. For bars, you can specify a
third coordinate which is the bottom of the bar (defaults to 0).

The format of a single series object is as follows:

  {
    color: color or number
    data: rawdata
    label: string
    lines: specific lines options
    bars: specific bars options
    points: specific points options
    xaxis: 1 or 2
    yaxis: 1 or 2
    clickable: boolean
    hoverable: boolean
    shadowSize: number
  }

You don't have to specify any of them except the data, the rest are
options that will get default values. Typically you'd only specify
label and data, like this:

  {
    label: "y = 3",
    data: [[0, 3], [10, 3]]
  }

The label is used for the legend, if you don't specify one, the series
will not show up in the legend.

If you don't specify color, the series will get a color from the
auto-generated colors. The color is either a CSS color specification
(like "rgb(255, 100, 123)") or an integer that specifies which of
auto-generated colors to select, e.g. 0 will get color no. 0, etc.

The latter is mostly useful if you let the user add and remove series,
in which case you can hard-code the color index to prevent the colors
from jumping around between the series.

The "xaxis" and "yaxis" options specify which axis to use, specify 2
to get the secondary axis (x axis at top or y axis to the right).
E.g., you can use this to make a dual axis plot by specifying
{ yaxis: 2 } for one data series.

"clickable" and "hoverable" can be set to false to disable
interactivity for specific series if interactivity is turned on in
the plot, see below.

The rest of the options are all documented below as they are the same
as the default options passed in via the options parameter in the plot
commmand. When you specify them for a specific data series, they will
override the default options for the plot for that data series.

Here's a complete example of a simple data specification:

  [ { label: "Foo", data: [ [10, 1], [17, -14], [30, 5] ] },
    { label: "Bar", data: [ [11, 13], [19, 11], [30, -7] ] } ]


Plot Options
------------

All options are completely optional. They are documented individually
below, to change them you just specify them in an object, e.g.

  var options = {
    series: {
      lines: { show: true },
      points: { show: true }
    }
  };

  $.plot(placeholder, data, options);


Customizing the legend
======================

  legend: {
    show: boolean
    labelFormatter: null or (fn: string, series object -> string)
    labelBoxBorderColor: color
    noColumns: number
    position: "ne" or "nw" or "se" or "sw"
    margin: number of pixels or [x margin, y margin]
    backgroundColor: null or color
    backgroundOpacity: number between 0 and 1
    container: null or jQuery object/DOM element/jQuery expression
  }

The legend is generated as a table with the data series labels and
small label boxes with the color of the series. If you want to format
the labels in some way, e.g. make them to links, you can pass in a
function for "labelFormatter". Here's an example that makes them
clickable:

  labelFormatter: function(label, series) {
    // series is the series object for the label
    return '<a href="#' + label + '">' + label + '</a>';
  }

"noColumns" is the number of columns to divide the legend table into.
"position" specifies the overall placement of the legend within the
plot (top-right, top-left, etc.) and margin the distance to the plot
edge (this can be either a number or an array of two numbers like [x,
y]). "backgroundColor" and "backgroundOpacity" specifies the
background. The default is a partly transparent auto-detected
background.

If you want the legend to appear somewhere else in the DOM, you can
specify "container" as a jQuery object/expression to put the legend
table into. The "position" and "margin" etc. options will then be
ignored. Note that Flot will overwrite the contents of the container.


Customizing the axes
====================

  xaxis, yaxis, x2axis, y2axis: {
    mode: null or "time"
    min: null or number
    max: null or number
    autoscaleMargin: null or number
    
    labelWidth: null or number
    labelHeight: null or number

    transform: null or fn: number -> number
    inverseTransform: null or fn: number -> number
    
    ticks: null or number or ticks array or (fn: range -> ticks array)
    tickSize: number or array
    minTickSize: number or array
    tickFormatter: (fn: number, object -> string) or string
    tickDecimals: null or number
  }

All axes have the same kind of options. The "mode" option
determines how the data is interpreted, the default of null means as
decimal numbers. Use "time" for time series data, see the next section.

The options "min"/"max" are the precise minimum/maximum value on the
scale. If you don't specify either of them, a value will automatically
be chosen based on the minimum/maximum data values.

The "autoscaleMargin" is a bit esoteric: it's the fraction of margin
that the scaling algorithm will add to avoid that the outermost points
ends up on the grid border. Note that this margin is only applied
when a min or max value is not explicitly set. If a margin is
specified, the plot will furthermore extend the axis end-point to the
nearest whole tick. The default value is "null" for the x axis and
0.02 for the y axis which seems appropriate for most cases.

"labelWidth" and "labelHeight" specifies a fixed size of the tick
labels in pixels. They're useful in case you need to align several
plots.

"transform" and "inverseTransform" are callbacks you can put in to
change the way the data is drawn. You can design a function to
compress or expand certain parts of the axis non-linearly, e.g.
suppress weekends or compress far away points with a logarithm or some
other means. When Flot draws the plot, each value is first put through
the transform function. Here's an example, the x axis can be turned
into a natural logarithm axis with the following code:

  xaxis: {
    transform: function (v) { return Math.log(v); },
    inverseTransform: function (v) { return Math.exp(v); }
  }

Note that for finding extrema, Flot assumes that the transform
function does not reorder values (monotonicity is assumed).

The inverseTransform is simply the inverse of the transform function
(so v == inverseTransform(transform(v)) for all relevant v). It is
required for converting from canvas coordinates to data coordinates,
e.g. for a mouse interaction where a certain pixel is clicked. If you
don't use any interactive features of Flot, you may not need it.


The rest of the options deal with the ticks.

If you don't specify any ticks, a tick generator algorithm will make
some for you. The algorithm has two passes. It first estimates how
many ticks would be reasonable and uses this number to compute a nice
round tick interval size. Then it generates the ticks.

You can specify how many ticks the algorithm aims for by setting
"ticks" to a number. The algorithm always tries to generate reasonably
round tick values so even if you ask for three ticks, you