R 使用ggplot和scale_x_离散显示x轴上一半的值

我有一个数据帧：

dput(df):

structure(list(Date = c("2008-11-28", "2008-12-31", "2009-01-30", 
"2009-02-27", "2009-03-31", "2009-04-30", "2009-05-29", "2009-06-30", 
"2009-07-31", "2009-08-31", "2009-09-30", "2009-10-30", "2009-11-30", 
"2009-12-31", "2010-01-29", "2010-02-26", "2010-03-31", "2010-04-30", 
"2010-05-31", "2010-06-30", "2010-07-30", "2010-08-31", "2010-09-30", 
"2010-10-29", "2010-11-30", "2010-12-31", "2011-01-31", "2011-02-28", 
"2011-03-31", "2011-04-29", "2011-05-31", "2011-06-30", "2011-07-29", 
"2011-08-31", "2011-09-30", "2011-10-31", "2011-11-30", "2011-12-30", 
"2012-01-31", "2012-02-29", "2012-03-30", "2012-04-30", "2012-05-31", 
"2012-06-29", "2012-07-31", "2012-08-31", "2012-09-28", "2012-10-31", 
"2012-11-30", "2012-12-31", "2013-01-31", "2013-02-28", "2013-03-29", 
"2013-04-30", "2013-05-31", "2013-06-28", "2013-07-31", "2013-08-30", 
"2013-09-30", "2013-10-31", "2013-11-29", "2008-11-28", "2008-12-31", 
"2009-01-30", "2009-02-27", "2009-03-31", "2009-04-30", "2009-05-29", 
"2009-06-30", "2009-07-31", "2009-08-31", "2009-09-30", "2009-10-30", 
"2009-11-30", "2009-12-31", "2010-01-29", "2010-02-26", "2010-03-31", 
"2010-04-30", "2010-05-31", "2010-06-30", "2010-07-30", "2010-08-31", 
"2010-09-30", "2010-10-29", "2010-11-30", "2010-12-31", "2011-01-31", 
"2011-02-28", "2011-03-31", "2011-04-29", "2011-05-31", "2011-06-30", 
"2011-07-29", "2011-08-31", "2011-09-30", "2011-10-31", "2011-11-30", 
"2011-12-30", "2012-01-31", "2012-02-29", "2012-03-30", "2012-04-30", 
"2012-05-31", "2012-06-29", "2012-07-31", "2012-08-31", "2012-09-28", 
"2012-10-31", "2012-11-30", "2012-12-31", "2013-01-31", "2013-02-28", 
"2013-03-29", "2013-04-30", "2013-05-31", "2013-06-28", "2013-07-31", 
"2013-08-30", "2013-09-30", "2013-10-31", "2013-11-29"), Variables = c("Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS HEDGNAV Index", "Korrelation Fond VS HEDGNAV Index", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX", "Korrelation Fond VS OMXN40 INDEX", 
"Korrelation Fond VS OMXN40 INDEX"), Value = c(0.543281082364437, 
0.527712775086864, 0.408808506706841, 0.429295911936136, 0.413869805084106, 
0.420679623586744, 0.486699140272165, 0.489646951704357, 0.482167209693269, 
0.476479729549409, 0.470318758286474, 0.445944951970354, 0.443399322259001, 
0.450016066763416, 0.426480550286595, 0.423371569969272, 0.45695040799057, 
0.431834238396871, 0.467511327603749, 0.468313995662446, 0.497800239085846, 
0.483892272485929, 0.461639835904741, 0.510817807699252, 0.607556423633874, 
0.635324016630525, 0.677123446245495, 0.64944374391215, 0.699596537117267, 
0.719111914210672, 0.646823640421409, 0.704957947272873, 0.711475445475265, 
0.586745307486821, 0.470189153059282, 0.496157837064293, 0.42998988517485, 
0.410086396037883, 0.434712079537519, 0.451209820436262, 0.439204849230259, 
0.458968925612488, 0.413432511226888, 0.352720907440874, 0.345869742666471, 
0.334881763959464, 0.364193270299568, 0.349099808200996, 0.344120170458358, 
0.321312279605764, 0.36780909986839, 0.45673262559758, 0.441745479560392, 
0.472657754486699, 0.460230404194416, 0.439767509233639, 0.451917786933249, 
0.502203230669925, 0.506491068871301, 0.326404602073815, 0.370217685029334, 
0.718957249305725, 0.692112042544696, 0.653190037272512, 0.600562794023062, 
0.577038569091474, 0.732404727204883, 0.701073092028334, 0.70024367927988, 
0.72760615710821, 0.760476468119078, 0.76494346961595, 0.74516226659605, 
0.739882810581542, 0.747631786072444, 0.726091015017154, 0.701735263628067, 
0.702742836045239, 0.710111045287843, 0.709534887923479, 0.660085062138124, 
0.68714771636425, 0.692372537364393, 0.653723068520449, 0.60219048444321, 
0.611238847460719, 0.615532490318692, 0.629099995821728, 0.696641041953563, 
0.699678945834638, 0.586283865406429, 0.624290876602801, 0.670695507419494, 
0.659774721518298, 0.71774709033755, 0.744569380783438, 0.816379470202153, 
0.837499193100422, 0.836198005977033, 0.84080909869627, 0.855061699261408, 
0.853368178821269, 0.851320045495211, 0.851777606811136, 0.814170256202011, 
0.815730122501554, 0.816104542127919, 0.791916561887601, 0.789829046533777, 
0.798421955468353, 0.768092583652463, 0.775993885935737, 0.782511954882627, 
0.792300623324247, 0.788792623730908, 0.777178875667974, 0.77530100406966, 
0.784668152948575, 0.723029746336548, 0.694308712557347, 0.657753481204441, 
0.656521122619321)), .Names = c("Date", "Variables", "Value"), row.names = c(NA, 
-122L), class = "data.frame")

然后我使用ggplot：

 CorrelationsBenchPlot<-ggplot(corres24mDfMelt, aes(x=Date,y=Value,group=Variables))+
  geom_line(aes(linetype=Variables,colour=Variables), size=1)+
  scale_y_continuous(breaks=seq(0.3,0.9,0.1),limits=c(0.3,0.9))+
  scale_x_discrete(breaks = corres24mDfMelt$Date[c(TRUE,FALSE)])+
  scale_colour_manual(values=c("black", "red", "green"))+theme_gdocs()+
  theme(axis.text.x  = element_text(angle=-90, hjust=0.5, size=8,colour="black",face="bold"),
        axis.text.y  = element_text(size=8,colour="black",face="bold"),
        legend.text = element_text(colour="black", size = 12, face = "bold"),
        legend.background = element_rect(fill="gray90", size=.5, linetype="dotted"), 
        plot.title = element_text(size = rel(1.6),face = "bold"),
        axis.title.y = element_blank(),
        axis.title.x=element_blank(),
        legend.title=element_blank(),
        legend.position=c(0.3, 0.11), 
        legend.position="none",
        legend.box="vertical")+
  labs(title = "2 Year Rolling Correlation\n")

---

corres24mDfMelt$Date

中的值不是唯一的，而是重复的（每个日期有两个值）。因此，命令

corres24mDfMelt$Date[c（TRUE，FALSE）]

仍然返回所有可能的值

您必须使用

唯一的

日期作为基础：

scale_x_discrete(breaks = unique(corres24mDfMelt$Date)[c(TRUE,FALSE)])