This function plots a previously calculated trend.

plot_trend(df, column_name, maptype = "toner-lite", showmap = TRUE)

## Arguments

df

Data frame containing at least 4 column: lat (latitude), lon (longitude), slope and an additional user-defined column column_name.

column_name

name of the column to use for grouping the results.

maptype

maptype. The default is "toner-lite", see ?ggmap::get_stamenmap for other options

showmap

set to FALSE to avoid plotting the map when running the function

## Value

Two plots, the first showing the distribution of the trend over a map, based on the slope of the linear model that describes the trend. The second plot shows a boxplot of the slope grouped based on the column column_name and slope can be user-defined (notice that in the plot the very extreme slope values are not displayed to avoid skewed visualisations).

## Examples

if (FALSE) {
# some fake data around London
df <- data.frame(lat = 51.5+runif(40,-0.3,0.3),
lon = 0+runif(40, -0.3,0.3),
slope = rnorm(40, c(rep(-0.4,20),rep(0.4,20))),
g = factor(c(rep("a",20), rep("b",20))))
theplots <- plot_trend(df, "g", maptype = "terrain-background")
theplots$A # map theplots$B + labs(subtitle = "Use ggplot usual commands to modify the plots") # boxplots

}