更改比例以设置边界

Question

这个问题是忘记记录你的代码的结果......我在设置ggplot图例的界限时遇到了麻烦...我希望它以5为间隔读取10到-10，其中0为0当然是中点。

ggmap(tcsec) + 
  geom_tile(data = secmodelobscount, 
            aes(x = long, y = lat, fill = diff), 
            alpha = 0.8) + 
  ggtitle("Southeast/Caribbean\nExperimental Model Simulation - Observations") + 
  scale_fill_gradient2("Difference", low = "blue", mid = "white", high = "red", 
                       midpoint = 0, breaks = c(10, 5, 0, -5, -10))

我对此代码的了解是......