I can't seem to pass math symbols to a contour label. Is this possible?
Example:
image(volcano)
contour(volcano, level=150, add=TRUE, label = "150") # works
contour(volcano, level=120, add=TRUE, label = expression(alpha)) # doesn't work
contour(volcano, level=110, add=TRUE, label = bquote(alpha)) # doesn't work
text(0.5,0.5, labels = bquote(alpha == .(120))) # works
text(0.2,0.5, labels = expression(paste(alpha, "= 150"))) # works
