title: How to suppress(remove) x tick labels of certain groups when using ggplot2 facet_wrap in R?
body: <p>Hi I have graph like this. As you can see I have chunky x tick labels in mathematical forms. </p>
  
  <pre><code>#example data
  data&lt;-data.frame(group=rep(c("Group A with a long name1","Group B with a long name2",
                           "Group C with a long name3", "Group D with a long name4",
                           "Group E with a long name5"), each=70),
               method=rep(c("method1","method2","method3","method4","method5","method6","method7"),times=50),
               estimate=c(rnorm(70, 40, 7), rnorm(70, 60, 10),rnorm(70, 150, 20),
                          rnorm(70, 400, 80),rnorm(70, 300, 65)))
  library(ggplot2)
  ggplot(data, aes(method, estimate))+
  geom_boxplot()+
  facet_wrap(~group, nrow=5, ncol=1, scales="free")+
  xlab(NULL)+
  ylab(bquote('estimate ('~individuals/km^2~')'))+
  scale_x_discrete(labels=expression(over('M*',A[ns]),frac('M*',ESA[sr]),
                                   frac(M[Ch],A[ns]),frac(M[Ch],ESA[sr]),
                                   frac(M[0],A[ns]),frac(M[0],ESA[sr]),
                                   sr[0],'sr*'))+
  theme_bw()+
  theme(strip.text = element_text(face = "italic", size=12),
      axis.title.x = element_text(size=18, margin=margin(10, 0, 0, 0)),  #margin(top, right, bottom, left)
      axis.text.x  = element_text(angle=0, size=8, vjust=0.5),
      axis.title.y = element_text(angle=90, size=14, margin=margin(0, 10, 0, 0)),
      axis.text.y  = element_text(angle=0, size=8),
      plot.title = element_text(colour="#990000", size=18),
      panel.grid.major = element_blank(),
      panel.grid.minor = element_blank(),
      strip.background = element_blank(),
      plot.margin=unit(c(0.3,0.5,0.5,0.5), "cm"),
      panel.border = element_rect(colour = "black"))
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/lV4Dc.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/lV4Dc.png" alt="enter image description here"></a></p>
  
  <p>Since the labels are redundant. How do I turn off the x tick labels of group A,B,C,D, and only keep those of group E's? I sincerely appreciate any comments and help.</p>