R: Polar plots considering changes in concentrations between two...

polarDiff {openair} | R Documentation

## Polar plots considering changes in concentrations between two time periods

### Description

This function provides a way of showing the differences in concentrations between two time periods as a polar plot. There are several uses of this function, but the most common will be to see how source(s) may have changed between two periods.

### Usage

    polarDiff(before, after, pollutant = "nox", x = "ws", limits = NA, ...)

### Arguments

`before` | A data frame that represents the "before" case. See `polarPlot` for details of different input requirements.
`after` | A data frame that represents the "after" case. See `polarPlot` for details of different input requirements.
`pollutant` | The pollutant to analyse.
`x` | The variable used for the radial axis (default = "ws").
`limits` | The colour scale limits e.g. `limits = c(-10, 10)`.
`...` | Other arguments to `polarPlot`.

### Details

While the function is primarily intended to compare two time periods at the same location, it can be used for any two data sets that contain the same pollutant. For example, data from two sites that are close to one another, or two co-located instruments.

The analysis works by calculating the polar plot surface for the `before` and `after` periods and then subtracting the `before` surface from the `after` surface.

### Value

Only plot at the moment.

### Examples

    ## Not run:

    before_data <- selectByDate(mydata, year = 2002)
    after_data <- selectByDate(mydata, year = 2003)

    polarDiff(before_data, after_data, pollutant = "no2")

    # with some options
    polarDiff(before_data, after_data, pollutant = "no2", cols = "RdYlBu", limits = c(-20, 20))

    ## End(Not run)

[Package openair version 2.8-5 Index]