This answer is based on my answer at Reading datafile entry by entry, except that the logic has been put into the readarray
package.
REVISED ANSWER
The revised readarray
package provides a more natural syntax than shown in the ORIGINAL ANSWER below. Additionally, it allows a user-specifiable data-separator character.
\documentclass{article}
\usepackage{readarray,filecontents}
\begin{filecontents*}{dataA.txt}
.15, 12, 13, 14
.20, 22, 23, 24
.25, 45.6, 33, Ending
\end{filecontents*}
\def\dataB{%
B.15 B12 B13 B14
B.20 B22 B23 B24
B.25 B32 B33 BEnding
}
\begin{document}
%
% This says to read the variable \dataA, stick it into an "array"
% called arA with a 4-column width
\readarraysepchar{,}
\readdef{dataA.txt}{\dataA}
\readarray\dataA\arA[-,\ncols]
%
\readarraysepchar{ }
\readarray\dataB\arB[-,4]
%
\noindent
The data in the 3,2 position of the dataA file is \arA[3,2]\\
The data in the 3,4 position of dataB is \arB[3,4]
\end{document}

ORIGINAL ANSWER (based on deprecated syntax)
It has some limitations, like using a space as an item separator (which I hope to change in a future release), but depending on the structure of your data, it could suffice. The important commands are readdef{file}{token}
to place the contents of a file into a \def
, \readArrayij{token}{arrayname}{width}
to read a token's contents into a array, and \Arrayij{arrayname}{row}{column}
to regurgitate a data entry of the array (with error checking).
If one saves the Excel spreadsheet as a text file, and if the data entries are without internal spaces, then this approach would suffice.
\documentclass{article}
\usepackage{readarray,filecontents}
\begin{document}
%
\begin{filecontents*}{dataA.txt}
.15 12 13 14
.20 22 23 24
.25 45.6 33 Ending
\end{filecontents*}
\readdef{dataA.txt}{\dataA}
\def\dataB{%
B.15 B12 B13 B14
B.20 B22 B23 B24
B.25 B32 B33 BEnding
}
%
% This says to read the variable \dataA, stick it into an "array"
% called arA with a 4-column width
\readArrayij{\dataA}{arA}{4}
\readArrayij{\dataB}{arB}{4}
\noindent
The data in the 3,2 position of the dataA file is \Arrayij{arA}{3}{2}\\
The data in the 3,4 position of dataB is \Arrayij{arB}{3}{4}
\end{document}
R
in the middle - it works well with spreadsheet files, you can do the extraction and preparation there. It then can produce LaTeX tables.