CODEWITHSUNDEEP
rgeocodingggmap
Mateus Maciel
Mateus Maciel

Reputation: 161

Convert latitude and longitude to city names, using R

I have a file data frame with informations about biochemical oxygen demand of some rivers, in Brazil. I'd like to transform the data that I have (in geographic coordinates) to the name of the city. How can I do that? I know there is a package called "ggmap" that could help me, but I'm note sure if it's the right one

Here is the link for the data: https://www.dropbox.com/s/rgkkqw50qqymil6/dbo.xls?dl=0

 state river             lat  long  year contagem  mean
  <chr> <chr>           <dbl> <dbl> <dbl>    <dbl> <dbl>
1 AL    Rio Mundaú      -9.60 -35.8  2007        5  3   
2 AL    Rio Mundaú      -9.60 -35.8  2010        5  2   
3 AL    Rio Mundaú      -9.60 -35.8  2011        9  3.78
4 AL    Zona dos Canais -9.71 -35.8  2007        5  2.2 
5 AL    Zona dos Canais -9.71 -35.8  2010        7  2   
6 AL    Zona dos Canais -9.71 -35.8  2011        9  2.11

Upvotes: 0

Views: 1451

Answers (1)

Aliyan Haq
Aliyan Haq

Reputation: 312

This is possible using the extract function from raster. Or also possible with the over function from the sp package. The approach I have taken below is done using the extract function:

I first used your data provided above to make a data frame, and then got the Brazil shapefile, and used it to extract the city name from the coordinates provided. Here is my code with comments:

library(raster)
library(sp)

#### Coordinates that will be used to search ###
state = c('AL','AL','AL','AL','AL','AL')
river = c('Rio Mundaú', 'Rio Mundaú', 'Rio Mundaú'  , 'Zona dos Can', 'Zona dos Can', 'Zona dos Canais')
lat = c(-9.60, -9.60, -9.60, -9.71, -9.71, -9.71)
long = c(-35.8, -35.8, -35.8, -35.8, -35.8, -35.8)
year = c(2007, 2010, 2011, 2007, 2010, 2011)
contagem = c(5, 5, 9, 5, 7, 9)
mean = c(3, 2, 3.78, 2.2, 2, 2.11)

brazil_data = data.frame(state, river, lat, long, year, contagem, mean)


### Getting the brazil shapefile
brazil = getData('GADM', country = 'Brazil', level = 3, type = "sp")

### Extracting the attributes from the shapefile for the given points
city_names = extract(brazil, brazil_data[, c("long", "lat")])[,12]

### Adding the city names to the Brazil data frame, with the coordinates
brazil_data$City = city_names

This is what we get at the end:

> brazil_data
  state           river   lat  long year contagem mean                 City
1    AL      Rio Mundaú -9.60 -35.8 2007        5 3.00 Santa Luzia do Norte
2    AL      Rio Mundaú -9.60 -35.8 2010        5 2.00 Santa Luzia do Norte
3    AL      Rio Mundaú -9.60 -35.8 2011        9 3.78 Santa Luzia do Norte
4    AL    Zona dos Can -9.71 -35.8 2007        5 2.20     Marechal deodoro
5    AL    Zona dos Can -9.71 -35.8 2010        7 2.00     Marechal deodoro
6    AL Zona dos Canais -9.71 -35.8 2011        9 2.11     Marechal deodoro

Hope this helps!

Upvotes: 2

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