[R] graphical behavior of a table of numbers

[Richard M. Heiberger]

## This example is from R-intro.pdf page 21 (R-3.3.2)

d <- outer(0:9, 0:9)
fr <- table(outer(d, d, "-"))
plot(as.numeric(names(fr)), fr, type="h",
            xlab="Determinant", ylab="Frequency")
## The y-axis tick marks are at c(-21,24,65).
## This seems to be because class(fr) == "table"

## Switching the class to array gives the more appropriate
## y-axis ticks at seq(0,500,100) .

fr.array <- fr
class(fr.array) <- "array"
plot(as.numeric(names(fr)), fr.array, type="h",
            xlab="Determinant", ylab="Frequency")


## I have a question and a recommendation.
## Question:
## Why are the y-axis ticks for the table defaulted to c(-21,24,65).
##
## Recommendation:
## Changed the example on page 21 to show the ticks at seq(0,500,100)?

## Rich