Formatted printing of matrices in R-CodePudding

I want to print entries of a matrix using formatted printing. Specifically I'd like to use "]" for the first column, and "%6.4f" for the remaining columns. The issue I am running into is that I have an arbitrary number of "decimal" columns and (sensibly), sprintf doesn't recycle its format string, e.g. sprintf("%6.4f", x[,1:4]) doesn't give you four columns of nicely printed numbers. I have some work arounds, but is there there something easier?

A reproducible example of what I would like to achieve:

set.seed(1234)
x = matrix(runif(20), ncol = 4)
x = cbind(1:5, x)
x = sprintf("] %6.4f %6.4f %6.4f %6.4f\n", x[,1], x[,2], x[,3], x[,4], x[,5])
cat("\n", x)

but the issue is that the dimension of x changes from run to run. I could programatically build the format string, and the input string and use eval and parse, but this seems like overkill.

Please don't suggest that I use the digits option of print - it doesn't do what I want.

CodePudding user response：

Another option that yields the same results:

set.seed(1234)
x = matrix(runif(20), ncol = 4)
x = cbind(1:5, x)

cbind(
  format(x[,1], digits = 0), 
  format(x[,2:ncol(x)], digits = 4)
  ) |>
  apply(1, \(z) paste(c("   ", z, "\n"), collapse = " ")) |>
  (\(w) cat("\n", w))()
#> 
#>      1 0.113703 0.640311 0.693591 0.837296 
#>      2 0.622299 0.009496 0.544975 0.286223 
#>      3 0.609275 0.232551 0.282734 0.266821 
#>      4 0.623379 0.666084 0.923433 0.186723 
#>      5 0.860915 0.514251 0.292316 0.232226

CodePudding user response：

set.seed(1234)
x = matrix(runif(20), ncol = 4)
x = cbind(1:5, x)
fmt = do.call( sprintf, c(list(
  paste("]", paste(rep("%6.4f",ncol(x)-1), collapse=" "),"\n")),
      lapply(1:ncol(x), \(i) x[,i])))
  
cat("\n", fmt)
#> 
#>      1 0.1137 0.6403 0.6936 0.8373 
#>      2 0.6223 0.0095 0.5450 0.2862 
#>      3 0.6093 0.2326 0.2827 0.2668 
#>      4 0.6234 0.6661 0.9234 0.1867 
#>      5 0.8609 0.5143 0.2923 0.2322

Try with another matrix dimensions

CodePudding user response：

This is much less elegant than the solutions above:

set.seed(1234)
x = matrix(runif(20), ncol = 4)
x = cbind(1:5, x)
numClusters = 4

printProbs = function(probs){
  fmtString = paste0("M  ", 
                     paste0(rep("   %6.4f", numClusters), collapse = " "),
                     "\n")
  inputsString = paste0("probs[, ", 1:(numClusters   1), "]", collapse = ", ")
  cmd = paste0("sprintf(\"", fmtString, "\", ", inputsString, ")")
  eval(parse(text = cmd))
}

cat(printProbs(x))

which yields:

> cat(printProbs(x))    
   1     0.1137    0.6403    0.6936    0.8373
    2     0.6223    0.0095    0.5450    0.2862
    3     0.6093    0.2326    0.2827    0.2668
    4     0.6234    0.6661    0.9234    0.1867
    5     0.8609    0.5143    0.2923    0.2322

I'm unsure why the first line skips a space, but I can fix this in code.