CODEWITHSUNDEEP
rggplot2mappingggmap
JimminyCricket
JimminyCricket

Reputation: 381

Issues with plotting coordinates ggmap

I have been trying to get the following dataset to map using ggmap and ggplot2 combination.

my dataframe -> head(dt.fil) containing 855 values

        lat     lon        airline
1  -73.9930 40.7480 Virgin America
2  -71.0200 42.3610 Virgin America
3 -118.4062 33.9454 Virgin America
4 -118.4041 33.9421 Virgin America
5  -96.9322 33.2145 US Airways
6 -118.3859 34.0220 United

my code is the following

map_airlines <- get_map(location = c(lon = mean(dt.fil$lon),
                                     lat = mean(dt.fil$lat)), zoom = 5,
                        maptype = "satellite", scale = 2)

# visualze the tweet locations
ggmap(map_airlines) +
  geom_point(data=dt.fil, aes(x=lon, y=lat, fill='red',
                              alpha=0.6, colour=airline)) +
  guides(fill=FALSE, alpha=FALSE)

I get the following errors

Warning messages:
1: In min(x) : no non-missing arguments to min; returning Inf
2: In max(x) : no non-missing arguments to max; returning -Inf
3: In min(x) : no non-missing arguments to min; returning Inf
4: In max(x) : no non-missing arguments to max; returning -Inf
5: Removed 835 rows containing missing values (geom_point).

I would really appreciate if somebody could help me with this :)

Upvotes: 2

Views: 375

Answers (1)

DCZ
DCZ

Reputation: 1744

There are 2 issues here:

  1. First of all, valid latitudes go from -90 up to +90 while valid longitudes go from -180 up to +180. Seeing as your latitudes don't fall in this range, i suppose you switched them. Therefore, in the rest of this example, I changed latitude into longitude and longitude into latitude. (Seeing as you're working with American airlines and datapoints are all located in the USA, this seemed reasonable).

    lon <- c(-73.9930 , -71.0200 , -118.4062 , -118.4041, -96.9322 , -118.3859 )
lat <- c(40.7480,  42.3610 , 33.9454 , 33.9421 , 33.2145 , 34.0220 )
airline <- c("Virgin America", "Virgin America", "Virgin America", "Virgin America", "US Airways", "United")
dt.fil <- data.frame(lat, lon, airline)

  2. The second problem is that your map is not large enough for the points to be plotted. To solve this, just adjust the zoom. (i took 3 instead of 5, just adjust it untill all datapoints fit).

    map_airlines <- get_map(location = c(lon = mean(dt.fil$lon),
                             lat = mean(dt.fil$lat)),
                zoom = 3,
                maptype = "satellite", scale = 2)

#visualze the tweet locations
ggmap(map_airlines) +
geom_point(data=dt.fil, aes(x=lon, y=lat, colour=airline), fill='red',
     alpha=0.6) +
guides(fill=FALSE, alpha=FALSE)

Upvotes: 2

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