Remove Antarctica from gglpot2 map - r

Question

I'm trying to reproduce this tutorial on how to plot a scatterplot-like map. Below is the full code and the output:
library(readr)
library(dplyr)
library(DT)
datatable(rladies, rownames = FALSE,
options = list(pageLength = 5))
url_csv <- 'https://raw.githubusercontent.com/d4tagirl/R-Ladies-growth-maps/master/rladies.csv'
rladies <- read_csv(url(url_csv)) %>%
select(-1)
library(ggplot2)
library(maps)
library(ggthemes)
world <- ggplot() +
borders("world", colour = "gray85", fill = "gray80") +
theme_map()
map <- world +
geom_point(aes(x = lon, y = lat, size = followers),
data = rladies,
colour = 'purple', alpha = .5) +
scale_size_continuous(range = c(1, 8),
breaks = c(250, 500, 750, 1000)) +
labs(size = 'Followers')
I want to remove Antartica from the map so that it doesn't take so much empty space. I tried to follow the solution from another similar Stackoverflow question as follows:
world <- map_data("world") %>%
filter(region != "Antarctica") %>%
ggplot(aes(long, lat, group = paste(region, group))) +
geom_polygon() +
coord_fixed()
map <- world +
geom_point(aes(x = lon, y = lat, size = followers),
data = rladies,
colour = 'purple', alpha = .5) +
scale_size_continuous(range = c(1, 8),
breaks = c(250, 500, 750, 1000)) +
labs(size = 'Followers')
But when I try to display the map I get the following error:
Error in paste(region, group) : object 'region' not found
Is there any other way to remove Antartica?
UPDATE: Failed subset attempt
countries <- map_data("world")
map_df <- subset(countries, region != "Antarctica")
map_base <- ggplot(data = map_df, mapping = aes(x = long, y = lat, group = group)) + coord_fixed(1.3) + geom_polygon(color = "black", fill = "gray")
# The base map is created successfully but I cannot plot points on it
map_base + geom_point(aes(x = lon, y = lat, size = followers), data = rladies, colour = 'purple', alpha = .5)
Error:
Error in eval(expr, envir, enclos) : object 'group' not found

Answer 1

Following on hrbmstr's advice, here is a solution using a proper projection and the sf package (with geom_sf from the development version of ggplot2). Note we use coord_sf to set the limits.
library(sf)
world <- map_data("world")
world.sf <- sf::st_as_sf(world, coords = c("long", "lat"), crs = 4326) %>%
group_by(group) %>%
summarize(do_union = FALSE) %>%
st_cast("POLYGON") %>%
ungroup()
world <- ggplot() +
geom_sf(data = world.sf, colour = "gray85", fill = "gray80") +
coord_sf(ylim = c(-50, 90), datum = NA) +
theme(panel.background = element_rect(fill = 'white'))
world +
geom_point(aes(x = lon, y = lat, size = followers),
data = rladies,
colour = 'purple', alpha = .5) +
scale_size_continuous(range = c(1, 8),
breaks = c(250, 500, 750, 1000)) +
labs(size = 'Followers', x = NULL, y = NULL)

Answer 2

We can also use coord_cartesian(ylim = c(-50, 90)) to set the y limits.
library(ggplot2)
library(maps)
library(ggthemes)
world <- ggplot() +
borders("world", colour = "gray85", fill = "gray80") +
theme_map() +
coord_cartesian(ylim = c(-50, 90))
map <- world +
geom_point(aes(x = lon, y = lat, size = followers),
data = rladies,
colour = 'purple', alpha = .5) +
scale_size_continuous(range = c(1, 8),
breaks = c(250, 500, 750, 1000)) +
labs(size = 'Followers')
map