Carpet plot
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A carpet plot may refer to a few different specific types of diagram.
Interaction of two independent variables
Probably the more common plot referred to as a carpet plot is one that illustrates the interacting behaviour of two independent variables, which among other things facilitates interpolation in both variables at once.
Named for its common application within areas such as material science and aeronautics[1][2] of showing elastic modulus in laminates.
Temporal raster plots
Another visualization that is sometimes called a carpet plot is a graphic representation of occurrences in a certain temporal relation. Each occurrence is registered in a Cartesian coordinate system, in which both axes show time, have different time resolutions: one axis shows slices of data, the other some sensible interval. A common example would be that one axis shows hours in a day, the other days in a year.
In a 2D plot, the value to be plotted is coded with an intensity or a color. In the 3D variant of the plot, it is often coded as a height[3]. When visualized, particularly the color-coded variant of the plot may easily show a carpet-like pattern.
Carpet plots make it easy to show time-based relations within a large sets of time-interval data and often make it easy to recognize local maxima and minima. Assuming the chosen time division is related to the events, it is also easy to recognize global and local patterns, such as recurrent events.
In the following example, the data is one year's worth of measurements of the outdoor temperatures in Augsburg, with one sample taken per hour. In the according carpet diagram, each column represents a day in the year and contains the values for that day (from 0:00 until 23:59).
Despite the high number of measure points (8760) it is easy to distinguish local and global patterns.
Note the similarity to beat graphs as described by Werner Van Belle[4].
References
- ^ "IHS Carpet Plots". Retrieved 17 December 2008.
- ^ "Use of Carpet Plots to represent functions of two variables". Retrieved 17 December 2008.
- ^ "'Whole building electrical power over time'". Retrieved 17 December 2008.
- ^ "BPM Measurement of Digital Audio by Means of Beat Graphs & Ray Shooting". Retrieved 17 December 2008.