R Workshop

Exercise

• In this exercise, we will create a dataframe comprising the names of Irish cities and towns, with their ITM coordinates.
• The first coordinate column shall contain the Eastings and the second shall contain the Northings

Create the dataset

Location <- c("Dublin","Cork","Mullingar","Ballymahon","Sligo","Doolin")
Easting <- c(715830,567469,643675,615785,568294,507565)
Northing <- c(734697,572117,753075,756895,835814,697069)

Ireland <- data.frame(Location,Easting,Northing)

Inspect the dataframe

head(Ireland)

##     Location Easting Northing
## 1     Dublin  715830   734697
## 2       Cork  567469   572117
## 3  Mullingar  643675   753075
## 4 Ballymahon  615785   756895
## 5      Sligo  568294   835814
## 6     Doolin  507565   697069

class(Ireland)

## [1] "data.frame"

Convert our dataframe to an {sf} object

This will transform our data set into a Simple feature collection

Ireland <- st_as_sf(Ireland, coords = c('Easting', 'Northing'), crs = 2157)

Again, we will inspect the data

head(Ireland)

## Simple feature collection with 6 features and 1 field
## Geometry type: POINT
## Dimension:     XY
## Bounding box:  xmin: 507565 ymin: 572117 xmax: 715830 ymax: 835814
## Projected CRS: IRENET95 / Irish Transverse Mercator
##     Location              geometry
## 1     Dublin POINT (715830 734697)
## 2       Cork POINT (567469 572117)
## 3  Mullingar POINT (643675 753075)
## 4 Ballymahon POINT (615785 756895)
## 5      Sligo POINT (568294 835814)
## 6     Doolin POINT (507565 697069)

class(Ireland)

## [1] "sf"         "data.frame"

Transform the CRS to WGS84

Ireland2 <- Ireland %>%
  st_transform(crs = "+proj=longlat +datum=WGS84")

head(Ireland2)

## Simple feature collection with 6 features and 1 field
## Geometry type: POINT
## Dimension:     XY
## Bounding box:  xmin: -9.377611 ymin: 51.90025 xmax: -6.260248 ymax: 54.27015
## Geodetic CRS:  +proj=longlat +datum=WGS84
##     Location                   geometry
## 1     Dublin POINT (-6.260248 53.34979)
## 2       Cork POINT (-8.472711 51.90025)
## 3  Mullingar POINT (-7.341315 53.52582)
## 4 Ballymahon POINT (-7.761738 53.56173)
## 5      Sligo POINT (-8.486748 54.27015)
## 6     Doolin POINT (-9.377611 53.01633)

A quick Plot

library(ggplot2)
ggplot(Ireland2) + geom_sf()