Closed Pweidemueller closed 1 year ago
Hello,
scatterPlot()
uses {hexbin}
to bin data into hexes for plotting. The lower number is inclusive and the upper number is exclusive. i.e., if the hex has 1 below it and 2 above it, that means that hex colour is associated with a single value. This can be simply demonstrated if we examine our data - we'd expect 2 observations where nox > 1000
and no2 > 150
, and that's what we see.
The uppermost limit (e.g, 3712) is inclusive, however - it does represent the highest count in the data.
library(openair)
scatterPlot(mydata, method = "hexbin")
dplyr::filter(mydata, nox > 1000, no2 > 150)
#> # A tibble: 2 × 10
#> date ws wd nox no2 o3 pm10 so2 co pm25
#> <dttm> <dbl> <int> <int> <int> <int> <int> <dbl> <dbl> <int>
#> 1 1999-01-22 11:00:00 NA 220 1144 155 6 139 18.8 7 104
#> 2 1999-01-22 14:00:00 0.96 250 1075 169 5 116 20.8 7.15 87
Created on 2023-03-23 with reprex v2.0.2
The number of bins is hard-coded I believe, but nowadays you might benefit from packages like {ggplot2}
for that sort of thing, which will give you a lot more control over the output:
library(ggplot2)
ggplot(openair::mydata, aes(nox, no2)) +
geom_hex() +
theme_bw() +
theme(aspect.ratio = 1) +
scale_fill_binned(type = "viridis", show.limits = TRUE,
breaks = c(0, 10, 20, 50, 100, 500, 2000, 4000)) +
labs(y = openair::quickText("no2"),
x = openair::quickText("nox"))
#> Warning: Removed 2438 rows containing non-finite values (`stat_binhex()`).
Created on 2023-03-23 with reprex v2.0.2
Hi there,
I'm plotting my data using the scatterPlot function with the
hexbin
method. It works very well! However, I can't find an explantion about the meaning of the numbers next to the hexagon legend (s. e.g. Fig. 17.2 https://bookdown.org/david_carslaw/openair/sec-scatterPlot.html).I guess they mean upper and lower bounds of counts collected in the color? Is the lower number exluding or including? Looking at Fig 17.2: does the 286 and 417 next to the most red hexagon mean that this hexagon includes all counts LARGER than 286 up to and including 417?
On a different note: Is the possible to set the number of bins? The default seems to produce 16 differently coloured hexagons. Can I set this number?