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Asked: 2026-06-10T01:18:47+00:00

I am trying to plot geographical location on a map. I am using ggplot2

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I am trying to plot geographical location on a map. I am using ggplot2 in combination with maps libraries.

Everything is nice except for on region that is very crowded. I would like to make a zoom in on this region but I am not able.

So I would like to zoom on the Galapagos island.
Here is the script I have used: 

library(ggplot2)
library(maps)

measurements <- read.csv("all_podo.count.csv", header=T)
allworld <- map_data("world")



d <- ggplot(measurements, aes(long, lat)) + 
geom_polygon(data = allworld, xlim = c(-50, 100), aes(x = long, y = lat, group = group),
colour = "grey70", fill = "grey70") +
geom_point(size = 0.7, shape = 8) + 
opts(axis.title.x = theme_blank(), 
axis.title.y = theme_blank()) +
geom_text(aes(label = name), size = 1, vjust = 0,  hjust = 0)
d

The measurements look like this:

structure(list(site_num = c(59L, 54L, 44L, 42L, 38L, 37L, 43L, 
39L, 36L, 40L, 34L, 35L, 33L, 41L, 32L, 31L, 30L, 29L, 28L, 27L, 
26L, 25L, 24L, 23L, 22L, 21L, 20L, 19L, 18L, 17L, 16L, 15L, 14L, 
13L, 12L, 11L, 10L, 7L, 8L, 9L, 1L, 3L, 6L, 5L, 79L, 77L, 78L, 
76L, 75L, 74L, 80L, 81L, 72L, 73L, 71L, 70L, 69L, 68L, 66L, 67L, 
65L, 63L, 64L, 62L, 60L, 61L), name = structure(c(44L, 43L, 42L, 
40L, 36L, 35L, 41L, 37L, 34L, 38L, 32L, 33L, 31L, 39L, 30L, 29L, 
28L, 27L, 26L, 25L, 24L, 23L, 22L, 21L, 20L, 19L, 18L, 17L, 16L, 
15L, 14L, 13L, 12L, 11L, 10L, 9L, 8L, 5L, 6L, 7L, 1L, 2L, 4L, 
3L, 64L, 62L, 63L, 61L, 60L, 59L, 65L, 66L, 57L, 58L, 56L, 55L, 
54L, 53L, 51L, 52L, 50L, 48L, 49L, 47L, 45L, 46L), .Label = c("GS000a", 
"GS000b", "GS000c", "GS000d", "GS001a", "GS001b", "GS001c", "GS002", 
"GS003", "GS004", "GS005", "GS006", "GS007", "GS008", "GS009", 
"GS010", "GS011", "GS012", "GS013", "GS014", "GS015", "GS016", 
"GS017", "GS018", "GS019", "GS020", "GS021", "GS022", "GS023", 
"GS025", "GS026", "GS027", "GS028", "GS029", "GS030", "GS031", 
"GS032", "GS033", "GS034", "GS035", "GS036", "GS037", "GS047", 
"GS051", "GS108a", "GS108b", "GS109", "GS110a", "GS110b", "GS111", 
"GS112a", "GS112b", "GS113", "GS114", "GS115", "GS116", "GS117a", 
"GS117b", "GS119", "GS120", "GS121", "GS122a", "GS122b", "GS123", 
"GS148", "GS149"), class = "factor"), lat = c(-15.143611, -10.131389, 
-1.9738889, 1.3891667, -0.3011111, 0.27222222, -0.020833334, 
-0.5938889, -0.2, -1.2283334, -1.2161111, -1.2169445, 1.2641667, 
-0.38305557, 5.552778, 5.64, 6.492778, 8.129167, 9.164444, 10.716389, 
18.036667, 20.5225, 24.174723, 24.488333, 32.506943, 36.003887, 
38.946945, 39.417778, 38.94, 41.09111, 41.485832, 43.63222, 45.111668, 
44.690277, 44.137222, 42.85278, 42.503056, 32.166668, 32.166668, 
32.166668, 31.175, 31.175, 31.175, 32.174835, -32.399166, -30.898333, 
-30.898333, -29.348888, -26.035, -23.21611, -6.3166666, -6.3166666, 
-4.613611, -4.613611, -4.635, -4.6625, -4.990278, -7.0075, -8.505, 
-8.505, -9.596945, -10.446111, -10.446111, -10.943611, -12.0925, 
-12.0925), long = c(-147.435, -135.44945, -95.014725, -91.81695, 
-91.651665, -91.63333, -91.19778, -91.06944, -90.83528, -90.42917, 
-90.422775, -90.319725, -90.295, -90.279724, -87.087776, -86.56528, 
-82.90389, -79.69111, -79.83611, -80.25445, -83.78472, -85.41361, 
-84.344444, -83.07, -79.263885, -75.39472, -76.41722, -75.504166, 
-74.685, -71.60222, -71.35111, -66.84722, -64.94666, -63.637222, 
-63.644444, -66.217224, -67.24, -64.5, -64.5, -64.5, -64.32433, 
-64.32433, -64.32433, -64.01017, 36.591946, 40.420277, 40.420277, 
43.215557, 50.123055, 52.30611, 39.009167, 39.009167, 55.50861, 
55.50861, 56.836113, 60.523056, 64.97667, 76.33139, 80.37556, 
80.37556, 84.1975, 88.30278, 88.30278, 92.05889, 96.88167, 96.88167
)), .Names = c("site_num", "name", "lat", "long"), class = "data.frame", row.names =     c(NA, 
-66L))

Can you help me ?

Thank you,

Simon

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1 Answer

  1. Editorial Team

    This shows you that the world map on package maps is not particularly high resolution by the time you get down to the level of the Galapagos:

    if (require("maps")) { 
world <- map_data("world") 
mid_range <- function(x) mean(range(x)) 
library(plyr) 
ggplot(world, aes(long, lat)) + 
   geom_polygon( aes(group = group), fill = "green", colour = "red")+
   ylim(c(-2, 1 )) + xlim( c(-93,-88) ) }

    enter image description here

    There doesn’t seem to be a group with that name. I’m thinking yoou might want to find a better shapefile for this project.:

    grep(“Is”, unique(world$region), value=TRUE)
    1 “Israel”
    [2] “Marshall Islands”
    [3] “Solomon Islands”
    [4] “Cook Islands”
    [5] “South Sandwich Islands”
    [6] “Sonsorol Island”
    [7] “Maug Island”
    [8] “Pitcairn Islands”
    [9] “Isle of Man”
    [10] “Andaman Islands”
    [11] “Northern Mariana Islands”
    [12] “Madeira Islands”
    [13] “Sin Cowe Island”
    [14] “Paracel Islands”
    [15] “Falkland Islands”
    [16] “Cayman Islands”
    [17] “Virgin Islands”
    [18] “Canary Islands”
    [19] “Spratly Island”
    [20] “Isle of Wight”

    An RSeek search finds several links. One of them to :

    http://downloads.cloudmade.com/americas/south_america/ecuador/galapagos/galapagos.shapefiles.zip

    “All of the files at downloads.cloudmade.com are based on data from OpenStreetMap and are licensed under the terms of the Creative Commons Attribution Share-Alike 2.0 license. If you use these files please make sure you attribute the OpenStreetMap community by including a link to http://www.openstreetmap.org.:

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