Boxplot in R showing the mean

Question

Does anybody know of a way of generating a boxplot in R with a line  or another symbol  in the value corresponding to the mean   Thank you

User · Answer

With ggplot2   p lt -qplot spray count data InsectSprays geom  boxplot   p lt -p stat summary fun y mean shape 1 col  red  geom  point   print p

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Based on the answers by  James and  Jyotirmoy Bhattacharya I came up with this solution   zx  lt - replicate  5  rnorm 50   zx means  lt -  colMeans zx  na rm   TRUE   boxplot zx  horizontal   FALSE  outline   FALSE  points zx means  pch   22  col    darkgrey   lwd   7     See this post for more details   If you would like to add points to horizontal box plots  please see this post

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Check chart Boxplot from package PerformanceAnalytics  It lets you define the symbol to use for the mean of the distribution  By default  the chart Boxplot data  command adds the mean as a red circle and the median as a black line  Here is the output with sample data  MWE   install packages PerformanceAnalytics      library PerformanceAnalytics  chart Boxplot cars speed

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I also think chart Boxplot is the best option  it gives you the position of the mean but if you have a matrix with returns all you need is one line of code to get all the boxplots in one graph    Here is a small ETF portfolio example   library zoo  library PerformanceAnalytics  library tseries  library xts   VTI prices   get hist quote instrument    VTI   start   2007-03-01   end  2013-03-01                           quote   c  AdjClose   provider    yahoo  origin   1970-01-01                            compression    m   retclass   c  zoo     VEU prices   get hist quote instrument    VEU   start   2007-03-01   end  2013-03-01                           quote   c  AdjClose   provider    yahoo  origin   1970-01-01                            compression    m   retclass   c  zoo     VWO prices   get hist quote instrument    VWO   start   2007-03-01   end  2013-03-01                           quote   c  AdjClose   provider    yahoo  origin   1970-01-01                            compression    m   retclass   c  zoo      VNQ prices   get hist quote instrument    VNQ   start   2007-03-01   end  2013-03-01                          quote   c  AdjClose   provider    yahoo  origin   1970-01-01                           compression    m   retclass   c  zoo     TLT prices   get hist quote instrument    TLT   start   2007-03-01   end  2013-03-01                           quote   c  AdjClose   provider    yahoo  origin   1970-01-01                            compression    m   retclass   c  zoo     TIP prices   get hist quote instrument    TIP   start   2007-03-01   end  2013-03-01                            quote   c  AdjClose   provider    yahoo  origin   1970-01-01                             compression    m   retclass   c  zoo     index VTI prices    as yearmon index VTI prices   index VEU prices    as yearmon index VEU prices   index VWO prices    as yearmon index VWO prices    index VNQ prices    as yearmon index VNQ prices   index TLT prices    as yearmon index TLT prices   index TIP prices    as yearmon index TIP prices    Prices z merge VTI prices  VEU prices  VWO prices  VNQ prices              TLT prices  TIP prices   colnames Prices z    c  VTI    VEU    VWO     VNQ    TLT    TIP    returnscc z   diff log Prices z    start returnscc z  end returnscc z  colnames returnscc z   head returnscc z    Return Matrix  ret mat   coredata returnscc z  class ret mat  colnames ret mat  head ret mat    Box Plot of Return Matrix   chart Boxplot returnscc z  names T  horizontal TRUE  colorset  darkgreen   as Tufte  F            mean symbol   20  median symbol      main  Return Distributions Comparison             element color    darkgray   outlier symbol   20             xlab  Continuously Compounded Returns   sort ascending F    You can try changing the mean symbol  and remove or change the median symbol  Hope it helped

User · Answer

abline h mean x     for a horizontal line  use v instead of h for vertical if you orient your boxplot horizontally   or  points mean x     for a point  Use the parameter pch to change the symbol  You may want to colour them to improve visibility too   Note that these are called after you have drawn the boxplot   If you are using the formula interface  you would have to construct the vector of means  For example  taking the first example from  boxplot   boxplot count   spray  data   InsectSprays  col    lightgray   means  lt - tapply InsectSprays count InsectSprays spray mean  points means col  red  pch 18    If your data contains missing values  you might want to replace the last argument of the tapply function with function x  mean x na rm T

[r] Boxplot in R showing the mean

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