## ----gadm, message=FALSE, warning=FALSE---------------------------------------
library(geodata)
adm <- gadm("TZA", level = 1, path=".")


## ----rdtp---------------------------------------------------------------------
library(osmdata)

roadtypes <- c("primary", "secondary", "tertiary")

getOSMdata <- function(obj, key, value) {
    b <- sp::bbox(obj)
    q <- osmdata::opq(b)
    q <- osmdata::add_osm_feature(q, key, value)
    d <- osmdata::osmdata_sp(q)
    d$osm_lines[, key]
}



## ----getOSM, eval=FALSE-------------------------------------------------------
## x <- lapply(seq_along(adm), function(i) getOSMdata(adm[i, ], "highway", roadtypes))


## ----processOSM, eval=FALSE---------------------------------------------------
## # combine the results for each area
## rd <- do.call(bind, x)
## # remove anything outside of Tanzania
## rd <- crop(rd, adm)
## # aggregate by type, also removing duplicates line parts
## roads <- aggregate(rd, "highway")


## ----simplr, eval=FALSE-------------------------------------------------------
## library(rmapshaper)
## roads <- ms_simplify(roads, keep=0.01)