plotmath              package:grDevices              R Documentation

_M_a_t_h_e_m_a_t_i_c_a_l _A_n_n_o_t_a_t_i_o_n _i_n _R

_D_e_s_c_r_i_p_t_i_o_n:

     If the 'text' argument to one of the text-drawing functions
     ('text', 'mtext', 'axis') in R is an expression, the argument is
     interpreted as a mathematical expression and the output will be
     formatted according to TeX-like rules.  Expressions can also be
     used for titles, subtitles and x- and y-axis labels (but not for
     axis labels on 'persp' plots).

_D_e_t_a_i_l_s:

     A mathematical expression must obey the normal rules of syntax for
     any R expression, but it is interpreted according to very
     different rules than for normal R expressions.

     It is possible to produce many different mathematical symbols,
     generate sub- or superscripts, produce fractions, etc.

     The output from 'demo(plotmath)' includes several tables which
     show the available features.  In these tables, the columns of grey
     text show sample R expressions, and the columns of black text show
     the resulting output.

     The available features are also described in the tables below:

       *Syntax*                     *Meaning*
       'x + y'                      x plus y
       'x - y'                      x minus y
       'x*y'                        juxtapose x and y
       'x/y'                        x forwardslash y
       'x %+-% y'                   x plus or minus y
       'x %/% y'                    x divided by y
       'x %*% y'                    x times y
       'x[i]'                       x subscript i
       'x^2'                        x superscript 2
       'paste(x, y, z)'             juxtapose x, y, and z
       'sqrt(x)'                    square root of x
       'sqrt(x, y)'                 yth root of x
       'x == y'                     x equals y
       'x != y'                     x is not equal to y
       'x < y'                      x is less than y
       'x <= y'                     x is less than or equal to y
       'x > y'                      x is greater than y
       'x >= y'                     x is greater than or equal to y
       'x %~~% y'                   x is approximately equal to y
       'x %=~% y'                   x and y are congruent
       'x %==% y'                   x is defined as y
       'x %prop% y'                 x is proportional to y
       'plain(x)'                   draw x in normal font
       'bold(x)'                    draw x in bold font
       'italic(x)'                  draw x in italic font
       'bolditalic(x)'              draw x in bolditalic font
       'list(x, y, z)'              comma-separated list
       '...'                        ellipsis (height varies)
       'cdots'                      ellipsis (vertically centred)
       'ldots'                      ellipsis (at baseline)
       'x %subset% y'               x is a proper subset of y
       'x %subseteq% y'             x is a subset of y
       'x %notsubset% y'            x is not a subset of y
       'x %supset% y'               x is a proper superset of y
       'x %supseteq% y'             x is a superset of y
       'x %in% y'                   x is an element of y
       'x %notin% y'                x is not an element of y
       'hat(x)'                     x with a circumflex
       'tilde(x)'                   x with a tilde
       'dot(x)'                     x with a dot
       'ring(x)'                    x with a ring
       'bar(xy)'                    xy with bar
       'widehat(xy)'                xy with a wide circumflex
       'widetilde(xy)'              xy with a wide tilde
       'x %<->% y'                  x double-arrow y
       'x %->% y'                   x right-arrow y
       'x %<-% y'                   x left-arrow y
       'x %up% y'                   x up-arrow y
       'x %down% y'                 x down-arrow y
       'x %<=>% y'                  x is equivalent to y
       'x %=>% y'                   x implies y
       'x %<=% y'                   y implies x
       'x %dblup% y'                x double-up-arrow y
       'x %dbldown% y'              x double-down-arrow y
       'alpha' - 'omega'            Greek symbols
       'Alpha' - 'Omega'            uppercase Greek symbols
       'infinity'                   infinity symbol
       'partialdiff'                partial differential symbol
       '32*degree'                  32 degrees
       '60*minute'                  60 minutes of angle
       '30*second'                  30 seconds of angle
       'displaystyle(x)'            draw x in normal size (extra spacing)
       'textstyle(x)'               draw x in normal size
       'scriptstyle(x)'             draw x in small size
       'scriptscriptstyle(x)'       draw x in very small size
       'underline(x)'               draw x underlined
       'x ~~ y'                     put extra space between x and y
       'x + phantom(0) + y'         leave gap for "0", but don't draw it
       'x + over(1, phantom(0))'    leave vertical gap for "0" (don't draw)
       'frac(x, y)'                 x over y
       'over(x, y)'                 x over y
       'atop(x, y)'                 x over y (no horizontal bar)
       'sum(x[i], i==1, n)'         sum x[i] for i equals 1 to n
       'prod(plain(P)(X==x), x)'    product of P(X=x) for all values of x
       'integral(f(x)*dx, a, b)'    definite integral of f(x) wrt x
       'union(A[i], i==1, n)'       union of A[i] for i equals 1 to n
       'intersect(A[i], i==1, n)'   intersection of A[i]
       'lim(f(x), x %->% 0)'        limit of f(x) as x tends to 0
       'min(g(x), x > 0)'           minimum of g(x) for x greater than 0
       'inf(S)'                     infimum of S
       'sup(S)'                     supremum of S
       'x^y + z'                    normal operator precedence
       'x^(y + z)'                  visible grouping of operands
       'x^{y + z}'                  invisible grouping of operands
       'group("(",list(a, b),"]")'  specify left and right delimiters
       'bgroup("(",atop(x,y),")")'  use scalable delimiters
       'group(lceil, x, rceil)'     special delimiters

_R_e_f_e_r_e_n_c_e_s:

     Murrell, P. and Ihaka, R. (2000) An approach to providing
     mathematical annotation in plots. _Journal of Computational and
     Graphical Statistics_, *9*, 582-599.

_S_e_e _A_l_s_o:

     'demo(plotmath)', 'axis', 'mtext', 'text', 'title', 'substitute'
     'quote', 'bquote'

_E_x_a_m_p_l_e_s:

     x <- seq(-4, 4, len = 101)
     y <- cbind(sin(x), cos(x))
     matplot(x, y, type = "l", xaxt = "n",
             main = expression(paste(plain(sin) * phi, "  and  ",
                                     plain(cos) * phi)),
             ylab = expression("sin" * phi, "cos" * phi), # only 1st is taken
             xlab = expression(paste("Phase Angle ", phi)),
             col.main = "blue")
     axis(1, at = c(-pi, -pi/2, 0, pi/2, pi),
          lab = expression(-pi, -pi/2, 0, pi/2, pi))

     ## How to combine "math" and numeric variables :
     plot(1:10, type="n", xlab="", ylab="", main = "plot math & numbers")
     theta <- 1.23 ; mtext(bquote(hat(theta) == .(theta)))
     for(i in 2:9)
         text(i,i+1, substitute(list(xi,eta) == group("(",list(x,y),")"),
                                list(x=i, y=i+1)))

     plot(1:10, 1:10)
     text(4, 9, expression(hat(beta) == (X^t * X)^{-1} * X^t * y))
     text(4, 8.4, "expression(hat(beta) == (X^t * X)^{-1} * X^t * y)",
          cex = .8)
     text(4, 7, expression(bar(x) == sum(frac(x[i], n), i==1, n)))
     text(4, 6.4, "expression(bar(x) == sum(frac(x[i], n), i==1, n))",
          cex = .8)
     text(8, 5, expression(paste(frac(1, sigma*sqrt(2*pi)), " ",
                                 plain(e)^{frac(-(x-mu)^2, 2*sigma^2)})),
          cex = 1.2)

