Combining paste and expression functions in plot labels

Question

Consider this simple example    labNames  lt - c  xLab   yLabl   plot c 1 10  xlab expression paste labName 1   x 2   ylab expression paste labName 2   y 2      What I want is for the character entry defined by the variable  labName    xLab  or  yLab  to appear next to the X 2 or y 2 defined by the expression    As it is  the actual text  labName  with a subscript is joined to the superscripted expression    Any thoughts

User · Answer

Very nice example using paste and substitute to typeset both symbols (mathplot) and variables at http://vis.supstat.com/2013/04/mathematical-annotation-in-r/

Here is a ggplot adaptation

library(ggplot2)
x_mean <- 1.5
x_sd <- 1.2
N <- 500

n <- ggplot(data.frame(x <- rnorm(N, x_mean, x_sd)),aes(x=x)) +
    geom_bar() + stat_bin() +
    labs(title=substitute(paste(
             "Histogram of random data with ",
             mu,"=",m,", ",
             sigma^2,"=",s2,", ",
             "draws = ", numdraws,", ",
             bar(x),"=",xbar,", ",
             s^2,"=",sde),
             list(m=x_mean,xbar=mean(x),s2=x_sd^2,sde=var(x),numdraws=N)))

print(n)

User · Answer

An alternative solution to that of  Aaron is the bquote   function  We need to supply a valid R expression  in this case LABEL   x 2 for example  where LABEL is the string you want to assign from the vector labNames  bquote evaluates R code within the expression wrapped in      and subsitutes the result into the expression   Here is an example   labNames  lt - c  xLab   yLab   xlab  lt - bquote   labNames 1     x 2  ylab  lt - bquote   labNames 2     y 2  plot c 1 10   xlab   xlab  ylab   ylab     Note the   just adds a bit of spacing  if you don t want the space  replace it with   and the two parts of the expression will be juxtaposed

User · Answer

Use substitute instead   labNames  lt - c  xLab   yLab   plot c 1 10        xlab substitute paste nn  x 2   list nn labNames 1          ylab substitute paste nn  y 2   list nn labNames 2

User · Answer

EDIT  added a new example for ggplot2 at the end  See  plotmath for the different mathematical operations in R   You should be able to use expression without paste  If you use the tilda     symbol within the expression function it will assume there is a space between the characters  or you could use the   symbol and it won t put a space between the arguments  Sometimes you will need to change the margins in you re putting superscripts on the y-axis   par mar c 5  4 3  4  2    0 1  plot 1 10  xlab   expression xLab   x 2   m -2        ylab   expression yLab   y 2   m -2        main  Plot 1       plot 1 10  xlab   expression xLab   x 2   m -2        ylab   expression yLab   y 2   m -2        main  Plot 2       plot 1 10  xlab   expression xLab   x 2   m -2        ylab   expression yLab   y 2   m -2        main  Plot 3       Hopefully you can see the differences between plots 1  2 and 3 with the different uses of the   and   symbols  An extra note  you can use other symbols such as plotting the degree symbol for temperatures for or mu  phi  If you want to add a subscript use the square brackets   plot 1 10  xlab   expression  Your x label    mu 3    phi        ylab   expression  Temperature      degree   C            Here is a ggplot example using expression with a nonsense example  require ggplot2    Or if you have the pacman library installed you can use p load to automatically download and load and attach add-on packages    require pacman    p load ggplot2   data   data frame x   1 10  y   1 10   ggplot data  aes x y     geom point        xlab expression bar yourUnits    g   m -2   OR   integral f x  dx  a b         ylab expression  Biomass  g per    m 3          theme bw

User · Answer

If x 2 and y 2 were expressions already given in the variable squared  this solves the problem   labNames  lt - c  xLab   yLab   squared  lt - c expression  x  2   expression  y  2    xlab  lt - eval bquote expression   labNames 1       squared 1   1       ylab  lt - eval bquote expression   labNames 2       squared 2   1        plot c 1 10   xlab   xlab  ylab   ylab    Please note the   1   behind squared 1   It gives you the content of  expression       between the brackets without any escape characters

[r] Combining paste() and expression() functions in plot labels

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