CODEWITHSUNDEEP
rr-sf
rctoni
rctoni

Reputation: 111

SF: from UTM to latitude/longitude

I have a set of UTM metric points that I would like to convert to latitude and longitude decimal points using the sf environment.

The dataset I have looks like this:

df <- data.frame(longitude=c(4585434,4588904,4586694),
                 latitude=c(430060.8,430960.8,432427.2),
                 street=c("74 JOSEP SERRANO", "30 LLOBERA","4 SANT ILDEFONS"),
                 number=c(45,68,34))

I have only been able to do it under the sp framework.

dfevpo <- SpatialPoints(df[, c("longitude","latitude")], proj4string=CRS("+proj=utm +zone=10")) 
longlats <- spTransform(dfevpo, CRS("+proj=longlat")) #transform

longlats.df <- as.data.frame(longlats)
longlats.df$.id <- as.numeric(rownames(longlats.df))

However, the resulting longlats.df dataset does not include all variables from the original dataset. I guess the order is the same and I could merge it with the original one. However, is there a more intuitive way of doing this? Ideally, I would like to use sf.

Upvotes: 3

Views: 3686

Answers (1)

UseR10085
UseR10085

Reputation: 8176

You can use the following code

library(sp)

df <- data.frame(longitude=c(4585434,4588904,4586694),
                 latitude=c(430060.8,430960.8,432427.2),
                 street=c("74 JOSEP SERRANO", "30 LLOBERA","4 SANT ILDEFONS"),
                 number=c(45,68,34))

#Convert the data frame to SpatialPointsDataFrame
coordinates (df)= ~longitude + latitude

#Assign a projection to it
proj4string(df) <- CRS("+proj=utm +zone=10")

#Projection transformation
longlats <- spTransform(df, CRS("+proj=longlat")) 

#Convert it to data frame
longlats.df <- as.data.frame(longlats)

If you want to implement the whole thing using sf package, you can use the following code

df <- data.frame(longitude=c(4585434,4588904,4586694),
                 latitude=c(430060.8,430960.8,432427.2),
                 street=c("74 JOSEP SERRANO", "30 LLOBERA","4 SANT ILDEFONS"),
                 number=c(45,68,34))

#Conversion of data frame to sf object
df_sf <- st_as_sf(x = df,                         
                  coords = c("longitude", "latitude"),
                  crs = "+proj=utm +zone=10")

#Projection transformation
sfc = st_transform(df_sf, crs = "+proj=longlat +datum=WGS84")

#Convert it to data frame
sfc_df <- as.data.frame(sfc)

Upvotes: 7

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