Bar Chart Widget
The Bar Chart
widget displays multiple
aggregate results in a single chart.
See in Figure 155, “Bar Chart” an example of how this widget may look like.
Figure 155. Bar Chart
Input Format
You can use the Bar Chart
widget to
visualize results of the groupBy()
and
top()
functions. Unlike a Pie
Chart
, a bar chart can be used to show multiple
aggregates results. If you provide several aggregate functions to the
function
argument of
groupBy()
it will display one result per
function.
Below is an example of how to display several series per category. Assume we have a service producing logs like the ones below:
2018-10-10T01:10:11.322Z host=web01 reponseTime=10.2ms
2018-10-10T01:10:12.172Z host=web01 reponseTime=2.6ms
2018-10-10T01:10:14.122Z host=web02 reponseTime=11.5ms
2018-10-10T01:10:15.312Z host=web01 reponseTime=14.7ms
2018-10-10T01:10:16.912Z host=web03 reponseTime=10.8ms
We would like to make a bar chart showing the maximum response time and the average response time per host.
groupBy(host, function=[max(responseTime), avg(responseTime)])
If you select the Bar Chart
widget type
from the Widget Type dropdown, this query will produce one bar chart
with three categories (one per host) and two series, one per aggregate
result (_max, and _avg).
Wide or Long Input Format
Among others, the Bar Chart
offers
the Input Data Format
property, whose Auto
mode looks at the query result
and automatically chooses the best interpretation of the data
between long or wide data format.
Long
data format is selected if there is more than one group field (made withgroupBy([a,b])
). Otherwise,Wide
data input format is selected.
In Long
data format mode, the first grouped field
contains the categories. Subsequent grouped fields are concatenated
to form the series. The first non-grouped field contains the
y-value. Example:
groupBy([status, internal])
Figure 156. Bar Chart Selecting Long Format
The data depicted in the below table view show what fields are visualized on the chart.
Figure 157. Long Format Table View
Wide
: All grouped fields are concatenated and form the category (x-axis). Each non grouped field becomes a series. Example:
groupBy(status, function=[avg(contentLength, as=content), avg(time, as="time")])
Figure 158. Bar Chart Selecting Wide Format
Note
A group field is the field used as the first argument to the
groupBy()
function.
Attention
Charts in existing dashboards (prior to the introduction of the
Auto
mode) with
groupBy([a,b])
queries and former default
mode still set to Wide
will look different as
they are automatically switched to Long
data
input format.
Widget Properties
Click the widget's
option to configure the following properties.General widget properties:
Title
The title of the widget as displayed in the dashboard. As in the example Figure 155, “Bar Chart”, it could be HTTP Methods.
Description
The description of the bar chart. This is free form text supporting markdown syntax. For example, This chart shows all HTTP methods, except
PUT
andHEAD
.This same description will appear in the dashboard as a tool-tip by hovering over the question mark on top of the widget.
Default time properties. The default widget time only works when Shared time is toggled off by default. Save the dashboard to set the current time selection as the default.
Time
Start
End
Styling properties:
Layout
Type
Grouped
— places series next to each other on a group for each categoryStacked
— places series on top of each other for each category
Category-Axis
Show Title checkbox
When ticked, shows the chosen title for the category (vertical) axis.
Title
Gives a title to the vertical axis.
Text Anchor
Controls where the labels are positioned under each bar. Valid options are:
Left
will bring labels closer to the bars.Center
Right
Angle
Modifies the angle of the label displayed under each bar.
Max Length
Sets the distance between the labels and the bottom of the widget. The distance is expressed in pixels, according to Cascading Style Sheets conventions. The more you increase the padding bottom, the more the size of the graph is reduced.
Value-Axis
Show Title checkbox
When ticked, shows the chosen title for the value (horizontal) axis.
Title
Gives a title to the horizontal axis.
Type
Linear
— quantitative scales that preserve proportional differences.Logarithmic
— quantitative scales particularly useful for plotting data that varies over multiple orders of magnitude.
Legend toggle, allows to show or hide the legend in the chart. If ticked, it prompts the following properties.
Labels
Options for displaying labels are:
Truncate
— shortens the length of the series for a better visualization within the chart. It is used in case of long labels that would exceed the maximum space allowed in the chart. It is the default option. Hover the mouse over a label, then press and hold ALT to momentarily see the full series.Show full
— shows the full name of the series, that is, the entire value is displayed in the label or tool-tip. In case of very long labels, it might affect their visibility within the chart. Hover the mouse over a label, then press and hold ALT to momentarily see the truncated series.
Position
Sets the position of the legend in the chart. Valid options are:
Right
Bottom
Show Title checkbox
Allows to show or hide the legend's title.
Title
Text field to enter the desired title for the legend when Show Title is ticked.
Bars
Show value on bars
Tick the box to show the given value for each bar.
Category Padding
Use this setting to control the distance between categories in the chart.
Series Padding
Use this setting to control the distance between bars within a category.
Max Series Count
Limits the number of series shown in a category. Series with the lowest cumulative sum across categories will be grouped into one series called "Other".
Input Data Format
How to interpret the result query data. Valid options are:
Auto
is selected by default and enables automatic detection of long or wide format — for details, see Wide or Long Input FormatWide
— data stored in wide format has a column for each series (variable) with the series name as the header and the values as rows. For example, this format is useful when data is grouped by a single field and multiple aggregate functions are used.Long
— data stored in long format has a single column for each named series (variable) and a single column with the values. For example, this format is useful when data is grouped by two fields.
Sorting
The default sorting is by X axis labels.
Order by Series
Specifies the name of the field to order the series by.
Order orders the series names alphabetically.
Valid options are:
Ascending
Descending
Series
Change the color of the bar series and assign them the title you want to see displayed in the chart.