I just started learning Latex for work but I'm having trouble with a code I'm writing. I'm trying to create a file that will take variables from another file and print them out with their assigned values in different settings. I have another file that has all the variables stored and will later input variables from matlab there.

This file is the one with my variables:

documentclass{article}

usepackage[utf8]{inputenc}

usepackage{calc}

input xintexpr.styrelax



title{Example of Variable Input}

author{Cordelia David}

date{April 2019}



newcommandStrawberries{34}

newcommandApples{14}

newcommandGrapes{431}

newcommandPears{56}

newcommandTomatoes{42}

newcommandTotalFruit{xintexpr Strawberries + Apples + Grapes + Pears + Tomatoes relax}



begin{document}



maketitle



Strawberries = Strawberries



Apples = Apples



Grapes = Grapes



Pears = Pears



Tomatoes = Tomatoes



Total of all Fruit = TotalFruit



end{document}

Which prints out mostly correctly, though I'm unsure why there's an exclamaton mark in front of the number for Total of All Fruits when compiled.

This is the file that calls that file:

documentclass{article} usepackage[utf8]{inputenc}



title{Example of Variable Input} author{Cordelia David} date{April 2019} input{Variables.tex} begin{document}







maketitle



section{Introduction}



We had Strawberries Strawberries for this year's harvest. Probably not enough.



end{document}

The problem I'm having is it will only compile the variables file, and anything I write in the main text won't get printed. Why is this? How do I fix this?

documentclass{article} usepackage[utf8]{inputenc}



title{Example of Variable Input}

author{Cordelia David} date{April 2019}

input{variables.tex}



begin{document}







maketitle



section{Introduction}



We had Strawberries Strawberries for this year's harvest. Probably not enough.



end{document}

with variables.tex :

newcommandStrawberries{34}

newcommandApples{14}

newcommandGrapes{431}

newcommandPears{56}

newcommandTomatoes{42}

newcommandTotalFruit{thenumexpr Strawberries + Apples + Grapes + Pears + Tomatoes relax}

Analysis of the Problem

Reading between the lines of what you posted, I see an external database being used to fill a document.

Proposed Approach

I will cut to the chase and recommend the datatool package.

Preamble

• article class




• load the two packages




• generate the database (can be removed when the database already exists)




• load the database

Document

• count the total fruit




• do various things to show the counts of various fruit

Code

documentclass{article}



% datatool does the database work

% xifthen parses for alternative input choices



usepackage{datatool,xifthen}



% the command to get how many fruit

% use howmany{fruitname} for the count with designation.

% use howmany[0]{fruitname} for the count without its designation.



newcommand*{howmany}[2][1]{%

    ifthenelse{equal{#1}{0}}

        {DTLfetch{fruits}{fruit}{#2}{count}}%

        {DTLfetch{fruits}{fruit}{#2}{count} #2}%

    }



% the file contents

% this is generated for the first time here

% it could instead be a CSV file that you have generated elsewhere

% (i.e. using a spreadsheet program)

% you will only need to generate this database ONE TIME



begin{filecontents*}{fruitdatabase.csv}

fruit, count

strawberries, 34

bananas, 10

cherries, 11

apples, 4

end{filecontents*}



% this command loads the databasebase to the document



DTLloaddb{fruits}{fruitdatabase.csv}



begin{document}



% this command sums the count column and stores the result

% in the variable totalcount



DTLsumcolumn{fruits}{count}{totalcount}



% here are some example use cases



We had howmany{strawberries} today.



We had howmany[0]{apples} golden yellow apples yesterday.



We had totalcount{} total fruits in the last two days.



end{document}

Even almost anything could be made via LaTeX macros, but if you want use variables, and make something complex with that variables, a pure LaTeX solution is not the easier. Consider the example below, taking the help of R power. If you change the line ...

Amounts <- c(34,14,431,56,42)

... with some other values, all in the document (table, plot and text) will change accordingly:

Fruits.pdf file:

Fruits.Rnw file:

documentclass{article}

usepackage{booktabs}

begin{document}



<<echo=F,results='asis'>>=

library(xtable) 

Fruits <- c("Strawberries","Apples","Grapes","Pears","Tomatoes")

Amounts <- c(34,14,431,56,42)

df <- data.frame(Fruits,Amounts)

print(xtable(df, digits=0), booktabs=T)

@



There are Sexpr{combine_words(tolower(df$Fruits))}. 

In total there are Sexpr{sum(df$Amounts)} fruits. 

We have a lot of Sexpr{tolower(df$Fruits[df$Amounts==max(df$Amounts)])} 

(Sexpr{max(df$Amounts)}),

but we need Sexpr{toupper(df$Fruits[df$Amounts==min(df$Amounts)])} !!



<<echo=F,results='asis',fig.height=4 >>=

barplot(df$Amounts,legend=df$Fruits,col=rainbow(5))

@



end{document}

To compile this you must have R and knitr package installed in your system, not only the TeX distribution. To compile it, the easiest way is load this file in Rstudio and click on "compile PDF" (this will convert Fruits.Rnw in Fruits.tex and then in Fruits.pdf).