Not getting fixed contour with "+" for grdcontour

Hello, so I was trying to get the coordinates for a 170 km contour using:

fig.grdcontour(grid='', interval = +170, D = "contoursl.ll")

I thought by adding “+” it would give me just the 170 km contour, but the dump contoursl.ll file also includes contours for multiples of 170 (340, 510, 680 and 850 km). May I have some help with this?

man page says

To indicate a single specific contour you must append a trailing comma to separate it from a contour interval.

So I think it should be interval = '170,' (or interval = "170,", I don’t know)

I think @Joaquim is right. You should use interval="170,". The PyGMT documentation for grdcontour needs updates.

Works great, thank you very much!