Heatmap

Atlas primarily supports visualizing data in line charts. As of 1.8, Atlas can also visualize via heatmaps using the :heatmap line style. The graph area is broken up into a series of cells and a count for each cell is incremented when a measurement falls within the cells boundaries. Colors or shades of colors then fill in cells based on the final count.

Percentiles¶

Heatmaps are particularly useful on top of percentile metrics to analyze the entire measurement range.

Note Using the log linear scale will help to highlight clustered regions of measurements via &scale=log-linear. The example also uses data not available in the demo Atlas instance.

/api/v1/graph?
  e=2012-01-01T00:00
  &no_legend=1
  &q=
    name,requestLatency,:eq,
    :percentile-heatmap,
    
  &scale=log-linear

ptile-heatmap

Bounds¶

The &heatmap_l= and &heatmap_u parameters can be used to narrow the range of cells displayed in a heatmap. Heatmap bounds act on the count of measurements in a cell and the palette colors or shades chosen. Depending on the bound limits, some cells may appear empty.

No Heatmap Bounds	With Bounds (`&heatmap_l=1.2&heatmap_u=1.3`)

name,sps,:eq, (,nf.cluster,),:by, :heatmap	name,sps,:eq, (,nf.cluster,),:by, :heatmap

Palette¶

The palette used for filling heatmap cells can be changed via the &heatmap_palette= parameter. By default, a color is chosen from the global palette (based on whether the heatmap is the first or a later expression). A gradient is then applied to that color with a lighter gradient representing smaller cell counts and darker representing larger counts.

Default Palette	Reds Palette (`&heatmap_palette=reds`)

name,sps,:eq, (,nf.cluster,),:by, :heatmap	name,sps,:eq, (,nf.cluster,),:by, :heatmap

Custom Palette¶

A custom palette may be provided by listing the hex colors to use in descending order, meaning the color to use for the highest cell counts must appear first.

/api/v1/graph?
  e=2012-01-01T00:00
  &q=
    name,sps,:eq,
    (,nf.cluster,),:by,
    :heatmap
  &heatmap_palette=(,8cd1b9,46adbc,2a91b8,1978b3,335ca9,413e95,361566,)

For further information, see Custom Color Palettes.

Order of Expressions¶

When overlaying expressions with a heatmap and using the default palette, the order of expressions determines the color gradient used for cells. For example, if the heatmap expression is second in the query, the second palette color will be used as the gradient:

Heatmap First	Heatmap Second

name,sps,:eq, (,nf.cluster,),:by, :heatmap, name,sps,:eq,	name,sps,:eq, name,sps,:eq, (,nf.cluster,),:by, :heatmap

Label¶

The label for the heatmap can be changed via the &heatmap_label= parameter. By default, the label is simply heatmap.

name,sps,:eq,
(,nf.cluster,),:by,
:heatmap

Scale¶

Similar to axis scales, the scale of the heatmap cell colors (or gradients) can be adjusted using the &heatmap_scale= parameter. By default, the scale is linear though any of the valid scales may be used.

Linear	Log Linear

name,sps,:eq, (,nf.cluster,),:by, :heatmap	name,sps,:eq, (,nf.cluster,),:by, :heatmap