Automatic numbering of a list in a table

Question

I know a way to automatically number. But at the same time, you still need to write the word \Rownum on a new line every time. Is there anything I can do to avoid writing this all the time?

    \documentclass[a4paper,12pt]{article}
\usepackage{cmap}
\usepackage[T2A]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english,russian]{babel}
\usepackage{caption}
\begin{document}
    \newcounter{rownum} 
    \setcounter{rownum}{0}
    \newcommand{\Rownum}{\stepcounter{rownum}
        \arabic{rownum}. }
\begin{tabular}{ |l|l| }
        number & value \
        \Rownum & 4.53 \
        \Rownum & 6.74 \
\end{tabular}
\end{document}

Answer 1

An implementation with expl3.

\documentclass{article}
\ExplSyntaxOn
% #1 body var #2 body #3 head
\cs_new_protected:Nn \__table_with_number:Nnn {
  \regex_split:nnN { \c{\\} } {#2} \l__table_line_seq
  \tl_clear_new:N #1
  \seq_map_indexed_inline:Nn \l__table_line_seq {
    \int_compare:nNnTF {##1} = {1} {
      \tl_put_right:Nn #1 { #3 & ##2 \\ }
    } {
      \tl_if_empty:nF {##2}
        { \tl_put_right:Nn #1 { \int_eval:n { ##1 - 1 }. & ##2 \\ } }
    }
  }
}
\NewDocumentEnvironment { Table } { O{number} m +b } {
  __table_with_number:Nnn \l__table_body_tl {#3} {#1}
  \begin{tabular}{#2}
    \l__table_body_tl
  \end{tabular}
}
\ExplSyntaxOff
\begin{document}
\begin{Table}{ll}
  value \
  1 \
  2.3 \
\end{Table}
\end{document}

Answer 2

Thanks everyone, I found the shortest, easiest and most effective way:

\documentclass[a4paper,12pt]{article}
\usepackage{cmap}
\usepackage[T2A]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[english,russian]{babel}
\usepackage{caption}
\usepackage{array,etoolbox} % For automatic numbering
\begin{document}
    \newcounter{rownum} % Declare a new counter for autonumbering rows in the table
    \setcounter{rownum}{0} % Set the initial value of the counter
    \newcommand{\Rownum}{\stepcounter{rownum} % Add one when calling a function
        \arabic{rownum} } % You can add a dot and a space at the end
\begin{tabular}{|>{\Rownum}l|l|}
    \multicolumn{1}{|l|}{№} & value \\
    & 4.53 \\
    & 6.74 \\
\end{tabular}

\end{document}

Answer 3

---

---

As commented, Bernard's solution is the simplest and therefore the best to use the counter, IMHO. Said that, another possibility is not set any counter nor any complex preamble.

If you don't know R and knitr, this solution is a bit like killing flies with cannon shots (although I strongly suggest you to know knitr if you often deal with numeric data and/or graphs in LaTeX documents). If you know how compile the test.Rnw below, is very simple, as any data frame output show by default row numbers, so you don't have to do anything special, just have some data frame (it can be imported from several formats as CSV or Excel or just typed in R code as showed in the example) and print it like a LaTeX table with xtable (or kable, or some others R packages):

% test.Rnw
\documentclass{article}
\usepackage{booktabs} % for better rules 
\begin{document}
<<table1, echo=F,results='asis'>>=
library(xtable)
# the data
df  <- data.frame( 
  value=c(4.53, 6.74,7.1),
  price=c(23,45,15))
# the table
xtable(df)
@
With a header for the counter 
(rather superfluous, but ...) 
and some table format:
<<table2,echo=F,results='asis'>>=
df$number <- rownames(df)  # numbers as variable
df <- df[,c(3,1,2)]        # numbers as first column
print(xtable(df,align="lccc",digits=c(0,0,2,0)),
include.rownames=F,booktabs=T) 
@
\end{document}