In jr-packages/jrSpatial: Jumping Rivers: Spatial Data Analysis using R

We'll start by loading the necessary packages.

library("sf")
library("dplyr")
library("tmap")
library("jrSpatial")

Question 1

1. Create a dataframe representing our current location and it's longitude and latitude. loc = data.frame(lon = , lat = ). You can use Google Maps to find our current longitude and latitude.

loc = data.frame(lon = -1.6053, lat = 54.9705)

1. In practical 1, we learned how to create a sf data frame from scratch using st_sf(). Because our coordinates are just numeric columns instead of a single geometry column, we can't use st_sf(). Instead we have to use st_as_sf() and specify the coordinate columns using the coords argument, like so

loc = st_as_sf(loc, coords = c("lon", "lat"))

1. Inspect the dataframe. Use the function st_is_longlat() to check whether the data is recognised as using longlat degrees. What about st_crs()?

st_is_longlat(loc)
st_crs(loc)
# no longlat because we have not set the coordinate ref system yet

1. Set the CRS to have epsg 4326 using st_set_crs() and then check st_is_longlat() again.

loc = st_set_crs(loc, 4236)
st_is_longlat(loc)

Question 2.

1. Load the shape files for New Zealand using data(nz_missing, package = "jrSpatial"). Plot the data using tm_shape() with tm_borders(). What do you notice?

data(nz_missing, package = "jrSpatial")
tm_shape(nz_missing) + tm_borders() + tm_fill()

# Part of New Zealand is missing.

1. The Canterbury region of New Zealand is missing from the data. Load in the Canterbury data using

data(canterbury, package = "jrSpatial")

Say we have two spatial data frame, x and y, we can row bind them by using

rbind(x, y)

Try to use rbind() to add the Canterbury row to the original New Zealand data. What does the output tell you?

nz = rbind(nz, canterbury)
# The two data sets have different CRS. R won't let us combine them.

1. The two data sets have different CRS. Find out the CRS of the New Zealand data using st_crs(). Then use st_transform() to transform the Canterbury data to use the same CRS as the rest of New Zealand. Combine the data with rbind() and plot the output.

st_crs(nz_missing)
canterbury = st_transform(canterbury, 4326)

nz = rbind(nz_missing, canterbury)

tm_shape(nz) + tm_borders() + tm_fill()

jr-packages/jrSpatial documentation built on Sept. 23, 2020, 2:31 p.m.