Does what it says on the tin.

DOWNLOAD THE CODE

#------------------------------
#-------- INFORMATION ---------
#------------------------------
# Plotting points from Hugh
# Rallinson's "Using Geochemical
# Data" book. Code compiled by
# Darren J. Wilkinson,
# Grant Inst. Earth Science
# The University of Edinburgh
# [email protected]
#------------------------------

# -------- CONTROLS ----------
y.max = 16
x.min = 35
x.max = 80
lab.size = 5
save = "/Users/s0679701/Desktop/"
filename = "test.png"
#------------------------------

# -------- LIBRARIES ----------
library (grid)
library (scales)
library (ggplot2)
#------------------------------

# -------- DON'T EDIT ----------
a = c(1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 8, 8)
x = c(41.0,41.0,52.5,50.0,52.5,57.6,63.0,63.0,45.0,45.0,61.0,63.5,45.0,52.0,57.0,63.0,69.0,45.0,49.4,52.0,52.0, 48.4,53.0,57.0,57.0,69.0,69.0,76.6,41.0,45.0)
y = c(0.500,7.000,14.000,15.126,14.000,11.700,7.000,0.500,0.500,5.000,13.500,14.830,5.000,5.000,5.900, 7.000,8.000,9.400,7.300,5.000,0.500,11.500,9.300,5.900,0.500,12.500,8.000,0.500,3.000,3.000)
lines = data.frame (a, x, y)

b = c("Picro-Basalt", "Basalt", "Basaltic Andesite", "Andesite", "Dacite", "Basanite", "Trachy Basalt", "Basaltic Trachyandesite", "Trachyandesite", "Trachydacite", "Rhyolite", "Tephrite", "Phonotephrite", "Tephriphonolite", "Trachyte", "Foidite", "Phonolite")
c = c(1:17)
x = c(43, 48.5, 54.5, 60, 68, 43, 48.75, 53, 57.5, 65, 75, 46, 49, 53, 65, 45, 58)
y = c(2, 2.5, 3, 3.5, 4, 6, 5.5, 6.5, 8.5, 9, 8, 8, 9.5, 11.5, 12, 13, 14)
labels = data.frame (b, x, y)

x = c(39.8,65.5) #MacDonald (1968)
y = c(0.35, 9.7) #MacDonald (1968)
sub = data.frame (x, y)
#------------------------------

# -------- BEGIN PLOT ----------

ggplot (lines, aes (x=x, y=y)) +

# Field Boundaries
geom_line (
aes(linewidth = factor (a))
) +

# Alkaline-Tholeiitic Line
geom_line (
data = sub,
aes (x=x, y=y),
linetype = "longdash"
) +

# Field Labels
geom_text (
data = labels,
aes(x = x, y = y, label = b),
size = lab.size
) +

scale_x_continuous (
name = (expression(paste("SiO"["2"], " (wt. %)"))),
limits = c(x.min, x.max)
) +

scale_y_continuous (
name = (expression(paste("Na"["2"], "O + K"["2"], "O", " (wt. %)"))),
breaks = c(seq(0, y.max, 2)),
limits = c(0, y.max)
) +

theme (
plot.title = element_text (vjust = 3, size = 20), #plot title
plot.margin = unit (c(3, 3, 3, 3), "lines"), #adjust the margins of the entire plot
panel.border = element_rect (colour = "black", fill = F, size = 2), #change the colour of the axes to black
panel.grid.major = element_blank (), # remove major grid
panel.grid.minor = element_blank (), # remove minor grid
panel.background = element_rect (fill = "white"), #makes the background transparent (white) NEEDED FOR INSIDE TICKS
legend.background = element_rect (fill = "white"),
legend.justification=c(1, 1),
legend.position = c(1, 1), # put the legend INSIDE the plot area
legend.key = element_blank (), # switch off the rectangle around symbols in the legend
legend.title = element_blank (), # switch off the legend title
legend.text = element_text (size = 15), #sets the attributes of the legend text
axis.title.x = element_text (vjust = -2, size = 20), #change the axis title
axis.title.y = element_text (vjust = -0.1, angle = 90, size = 20), #change the axis title
axis.text.x = element_text (size = 17, vjust = -0.25, colour = "black"), #change the axis label font attributes
axis.text.y = element_text (size = 17, hjust = 1, colour = "black"), #change the axis label font attributes
axis.ticks = element_line (colour = "black", size = 0.5), #sets the thickness and colour of axis ticks
axis.ticks.length = unit(-0.25 , "cm"), #setting a negative length plots inside, but background must be FALSE colour
axis.ticks.margin = unit(0.5, "cm") # the margin between the ticks and the text
)

ggsave (paste (save, filename), height = 12, width = 18, dpi = 75)