更改 ggplot2 中的 Y 轴分隔符

我有这段代码可以给出如下所示的图表：

d=ggplot(df, aes(x=Year, y=NAO_Index, width=.8)) +
+ geom_bar(stat="identity", aes(fill=NAO_Index>0), position='identity', col = 'transparent') +
+ theme_bw() + scale_fill_manual(values=c("royalblue", "firebrick3"), name="NAO Oscillation", labels=c("Negative", "Positive"), guide=guide_legend(reverse=TRUE)) +
theme(legend.position=c(0.06, 0.92)) + 
+ theme(axis.title.x=element_text(vjust=-0.2)) +
+ geom_line(data=dfmoveav, aes(x=Year ,y=moveav)) +
+ ylab("NAO Index") +
+ ggtitle("NAO Index between 1860 and 2050") +
+ scale_x_continuous(breaks=c(seq(1860,2050,10))) +
+ scale_y_continuous(breaks=c(seq(-3.5,3.5,0.5)))

我只关心最后一行。在图中，y 轴仅从 -3 到 2.5。如何将其从 -3.5 变为 3.5，使其均匀？

我确信我犯了一个简单的错误，但无法弄清楚！

Many thanks in advance.

你快到了。尝试设定限制。

d=ggplot(df, aes(x=Year, y=NAO_Index, width=.8)) +
+ geom_bar(stat="identity", aes(fill=NAO_Index>0), position='identity', col = 'transparent') +
+ theme_bw() + scale_fill_manual(values=c("royalblue", "firebrick3"), name="NAO Oscillation", labels=c("Negative", "Positive"), guide=guide_legend(reverse=TRUE)) +
theme(legend.position=c(0.06, 0.92)) + 
+ theme(axis.title.x=element_text(vjust=-0.2)) +
+ geom_line(data=dfmoveav, aes(x=Year ,y=moveav)) +
+ ylab("NAO Index") +
+ ggtitle("NAO Index between 1860 and 2050") +
+ scale_x_continuous(breaks=c(seq(1860,2050,10))) +
+ scale_y_continuous(breaks=c(seq(-3.5,3.5,0.5)), limits = c(-3.5, 3.5))

更多相关信息here http://docs.ggplot2.org/0.9.3.1/scale_continuous.html

要将线条映射到图例中，您应该将变量映射到美学。但这并不简单，您会找到避免这种方法的参考资料。

df <- data.frame(year=factor(seq(1:10)),
                 nao = rnorm(10, 0, 2),
                 mov = rnorm(10, 0,3))
df2 <- data.frame(year=factor(seq(1:10)),
                  mov = df$nao+rnorm(10, 0, 0.1),
                  g = .1)
ggplot() +
  geom_bar(data = df, aes(x=year, y=nao, fill=nao > 0), width=.8, 
           stat="identity", position ='identity', col = 'transparent') +
  geom_line(data = df2, aes(x = year, y = mov, group = g, size = g)) +
  scale_fill_manual(values=c("royalblue", "firebrick3"),
                    name="NAO Oscillation",
                    labels=c("Negative", "Positive"),
                    guide=guide_legend(reverse=TRUE)) +
  scale_size('Trend', range = 1, labels = 'Moving\naverage') +
  ggtitle("NAO Index between 1860 and 2050") +
  scale_y_continuous(breaks=c(seq(-5,5,0.5)), limits = c(-5, 5)) +
  ylab("NAO Index") +
  theme(legend.position = c(0.07, 0.80),
        axis.title.x = element_text(vjust= -0.2),
        legend.background = element_blank())

这可能不是将变量映射到美学的最佳方法。