title: How to increase the space between grouped bars in ggplot2?
body: <p>[Data and code to produce plot at the end of the post]</p>
  
  <p>Using ggplot, I plotted a bargraph with error bars, bars are grouped by two factors (one on X axis, one with fill). <strong>I would like to increase the green distance between the groups on the xaxis</strong> to make the plot easier to read:
  <img src="https://i.stack.imgur.com/JZZOY.png" alt="example"></p>
  
  <p>The closest thing to a solution on stackoverflow I found <a href="https://stackoverflow.com/questions/6085238/adding-space-between-bars-in-ggplot2">here</a> (where someone asked my question in an unanswered comment), <a href="https://stackoverflow.com/questions/25887066/remove-space-between-bars-ggplot2">here</a>, <a href="https://stackoverflow.com/questions/31724387/spacing-between-bars-in-a-grouped-stack-chart-using-ggplot">here</a>, but I didn't manage to apply these without massing up the error bars. Can someone point me to the right parameter to tweak? </p>
  
  <p>Data:</p>
  
  <pre><code>structure(list(Condition = c("Difficult", "Easy", "Difficult", 
  "Easy", "Difficult", "Easy", "Difficult", "Easy", "Easy", "Difficult", 
  "Easy", "Difficult"), Measure = c("Competence", "Competence", 
  "Value", "Value", "Interest", "Interest", "JOL", "JOL", "Difficulty", 
  "Difficulty", "Effort", "Effort"), mean = c(5.5, 4.72, 4.04, 
  5.39, 3.51, 3.77, 4.34, 4.61, 3.51, 1.51, 3.44, 1.73), sd = c(1.26, 
  1.62, 1.94, 1.34, 1.46, 1.46, 1.73, 1.68, 1.5, 0.86, 1.53, 1.1
  ), se = c(0.14, 0.18, 0.22, 0.15, 0.16, 0.16, 0.19, 0.19, 0.17, 
  0.1, 0.17, 0.12), s.size = c(80, 80, 80, 80, 80, 80, 80, 80, 
  80, 80, 80, 80)), .Names = c("Condition", "Measure", "mean", 
  "sd", "se", "s.size"), row.names = c(NA, -12L), class = "data.frame")
  </code></pre>
  
  <p>which is:</p>
  
  <pre><code>   Condition    Measure mean   sd   se s.size
  1  Difficult Competence 5.50 1.26 0.14     80
  2       Easy Competence 4.72 1.62 0.18     80
  3  Difficult      Value 4.04 1.94 0.22     80
  4       Easy      Value 5.39 1.34 0.15     80
  5  Difficult   Interest 3.51 1.46 0.16     80
  6       Easy   Interest 3.77 1.46 0.16     80
  7  Difficult        JOL 4.34 1.73 0.19     80
  8       Easy        JOL 4.61 1.68 0.19     80
  9       Easy Difficulty 3.51 1.50 0.17     80
  10 Difficult Difficulty 1.51 0.86 0.10     80
  11      Easy     Effort 3.44 1.53 0.17     80
  12 Difficult     Effort 1.73 1.10 0.12     80
  </code></pre>
  
  <p>Code that I used to make the plot (excuse the comments, I'm learning how to use ggplot and find it helpful to take notes)</p>
  
  <pre><code>library(ggplot2)
  ggplot(DF, aes(x=Measure, y=mean,fill=Condition)) + 
    geom_bar(stat="identity",
             colour="black",    # Black outline for all
             position=position_dodge())+# Put bars side-by-side instead of stacked
    geom_errorbar(aes(ymin=mean-se, ymax=mean+se),
                  position=position_dodge(.9), 
                  width=.25)+
    #order the groups on the xaxis
    scale_x_discrete(limits = c("Interest", "Value","Effort","Difficulty","Competence","JOL"))+
    coord_cartesian(ylim=c(0,7)) +
    #change color of bars
    scale_fill_manual(values=c("#ffcc00ff","#ffffff"), name = "Condition") + 
    #change ticks on yaxis
    scale_y_continuous(breaks=seq(0,7,by =1)) + 
    geom_hline(yintercept=0) +
    geom_vline(xintercept=0)+
    theme_bw()+
    labs(x="", y = "Rating (0-7)")+
    theme(axis.line.y = element_line(color="black"),
          axis.title.y = element_text(margin = margin(r=8)),
          axis.title.x = element_text(margin = margin(r=25)),
          panel.background = element_rect(fill = NA),
          panel.grid.major = element_blank(),
          panel.border = element_blank())
  </code></pre>