A dBm to Milliwatts Conversion Table

dbm_table.pdf

dbm_table.r

# Create one or more LaTeX files each containing a dBm to milliwatts conversion
# table. The table is a LaTeX 'tabular' and has three columns:
#   1. dBm
#   2. Milliwatts (absolute notation)
#   3. Milliwatts (scientific notation)
#
# Prerequisites: R package 'xtable' installed
#
# Daniel Weibel <danielmweibel@gmail.com> December 2015 
#------------------------------------------------------------------------------#

dBm2mW <- function(dbm) {
  # Convert dBm to milliwatts
  #----------------------------------------------------------------------------#
  10^(dbm/10)
}

mW2dBm <- function(mw) { 
  # Convert milliwatts to dBm (not used in this file)
  #----------------------------------------------------------------------------#
  log10(mw) * 10
}

FormatSciLatex <- function(v, digits) {
  # Format a number in scientific format for printing with LaTeX.
  # Example: 0.063096 ==> "6.3906 x 10^{-2}"
  #----------------------------------------------------------------------------#
  sci <- formatC(v, digits=digits, format="e")  # Format: "6.3096e-02"
  n   <- nchar(sci)                             # Length of each number
  exp <- strtoi(substr(sci, n-1, n), base=10)   # Exponent (last two chars)
  sig <- substr(sci, n-2, n-2)                  # Exponent sign (3rd-last char)
  sig <- ifelse(sig == "-", "-", "")
  fac <- as.numeric(substr(sci, 1, n-4))        # Factor (chars up to "e")
  paste0(fac, " x 10^{", sig, exp, "}")
}

XtableNoWarnings <- function(...) {
  # Run xtable without warnings (e.g. due to non-standard 'align' specifiers)
  #----------------------------------------------------------------------------#
  options(warn=-1)
  xt <- xtable(...)
  options(warn=0)
  xt
}

library(xtable)
# dBm values to include in each table (each list elt. will become a table)
dbm.groups   <- list(0:-69, -70:-139)
# File name for each table
file.groups  <- c("tab_1.tex", "tab_2.tex")
# Column alignment for each table (will be put in \begin{tabular}{...})
align.groups <- c("ld{3.0}d{10}x{6.4}", "ld{4.0}d{17}x{6.5}")
# Table header (same for all tables)
colnames     <- c("\\multicolumn{1}{l}{dBm}",
                  "\\multicolumn{1}{l}{Milliwatts}",
                  "\\multicolumn{1}{l}{Milliwatts}")
# Number of digits after decimal point in 2nd column of tables
digits       <- 5

i <- 1
for (dbm in dbm.groups) {
  mw.raw <- dBm2mW(dbm)
  mw.abs <- formatC(mw.raw, digits=digits, format="fg")
  mw.sci <- FormatSciLatex(mw.raw, digits=digits-1)
  df <- data.frame(dbm, mw.abs, mw.sci)
  colnames(df) <- colnames
  xt <- XtableNoWarnings(df, align=align.groups[i])
  print(xt, include.rownames=FALSE,
            floating=FALSE,
            sanitize.text.function=identity,
            file=file.groups[i])
  i <- i + 1
}

dbm_table.tex

% Place two dBm conversion tables, as produced by dbm_table.r, next to each
% other on an A4 page.
%
% Daniel Weibel <danielmweibel@gmail.com> December 2015
%------------------------------------------------------------------------------%

\documentclass{article}
\usepackage[a4paper,margin=1cm]{geometry}
\usepackage{dcolumn}
% Column type with alignment on decimal dot (or other char). The argument is
% the max. number of decimal places in the column (defines column width).
% Note: for the headers of these columns use e.g. \multicolumn{1}{|l|}{Text}
\newcolumntype{d}[1]{D{.}{.}{#1}}       % Align on decimal dot
\newcolumntype{x}[1]{D{x}{\times}{#1}}  % Align on 'x' and replace with '\times'

% Disable page numbers
\pagenumbering{gobble}

\begin{document}

\small
\begin{center}
\parbox{0.39\textwidth}{\centering\include{tab_1}}
\parbox{0.45\textwidth}{\centering\include{tab_2}}
\end{center}

\end{document}