<> <> Using Stata dynamic tags in a text file with the dyndoc command =============================================================== Let us consider an example where we study the **mpg** and **weight** variables in **auto.dta**. In our examples below, we will first write the commands so that they will be displayed in our target HTML file. Then, we will write the commands so that Stata will process the Stata dynamic tags, displaying the results of the Stata commands in the target HTML file. We first use the **sysuse** command to load the dataset and then describe the data using the **describe** command. ~~~~ ```{stata} sysuse auto, clear describe ``` ~~~~ This produces the following Stata results: ```{stata} sysuse auto, clear describe ``` Now, we want to check if **mpg** is always greater than 0 and less than 100. We use the **assert** command to perform the check. In this case, we do not want to include any output in the target HTML file, so we use the **quietly** attribute to modify the behavior of the **dd_do** Stata dynamic tag. ~~~~ ```{stata, echo=FALSE, results="hide"} assert mpg > 0 & mpg < 100 ``` ~~~~ ```{stata, echo=FALSE, results="hide"} assert mpg > 0 & mpg < 100 ``` If the data do not satisfy the conditions, **dyndoc** will fail with an error message, which will occur if we run the same **assert** command in a do-file. Next, we want to summarize the **weight** variable: ~~~~ ```{stata} summarize weight ``` ~~~~ This produces the following in the target HTML file: ```{stata} summarize weight ``` We want to use the minimum and maximum values of **weight** in a sentence. Instead of copying and pasting the numbers from the **summarize** output, we can use the **dd_display** Stata dynamic tag with the **r(min)** and **r(max)** stored results: ~~~~ > The variable weight has minimum value `s %4.2f `r(min)'` and has maximum value `s %4.2f `r(max)'`. ~~~~ This produces the following in the target HTML file: > The variable weight has minimum value `s %4.2f `r(min)'` and has maximum value `s %4.2f `r(max)'`. The **dd_display** dynamic tag uses Stata's **display** command to evaluate expressions. It can be used as a calculator. For example, if we want to include the $$range = max - min$$ in a sentence, instead of calculating the number and then copying and pasting it, we can use ~~~~ > The variable weight has range `s %4.2f `r(max)'-`r(min)'`. ~~~~ which produces the following in the target HTML file: > The variable weight has range `s %4.2f `r(max)'-`r(min)'`. Now, we want to graph **mpg** and **weight** using a scatterplot. We use the **dd_do** tag with the **nooutput** attribute to generate the scatterplot first. The **nooutput** attribute leaves the command in the output only, ~~~~ ```{stata, results="hide"} scatter mpg weight, mcolor(blue%50) ``` ~~~~ which generates a scatterplot of **mpg** and **weight** with 50% opacity color markers. ```{stata, results="hide"} scatter mpg weight, mcolor(blue%50) ``` Now, we want to export the graph to a file and include an image link to the file. ~~~~ <> <> <> ~~~~ This produces a graph of 400 pixels high. <>