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}
<<dd_do>>
sysuse auto, clear
describe
<</dd_do>>
```
<<dd_do: quietly>>
capture graph describe Graph
local checkdate = "`r(command_date)' `r(command_time)'"
<</dd_do>>
<<dd_skip_if: ="``gdate''"~="" & "``gdate''"=="`checkdate'">>
<<dd_graph>>
<<dd_skip_end>>
<<dd_do: quietly>>
local `gdate' = "`r(command_date)' `r(command_time)'"
<</dd_do>>
This produces the following Stata results:
. sysuse auto, clear
(1978 Automobile Data)
. describe
Contains data from D:\Programs\Stata15\ado\base/a/auto.dta
obs: 74 1978 Automobile Data
vars: 12 13 Apr 2016 17:45
size: 3,182 (_dta has notes)
------------------------------------------------------------------------------------
storage display value
variable name type format label variable label
------------------------------------------------------------------------------------
make str18 %-18s Make and Model
price int %8.0gc Price
mpg int %8.0g Mileage (mpg)
rep78 int %8.0g Repair Record 1978
headroom float %6.1f Headroom (in.)
trunk int %8.0g Trunk space (cu. ft.)
weight int %8.0gc Weight (lbs.)
length int %8.0g Length (in.)
turn int %8.0g Turn Circle (ft.)
displacement int %8.0g Displacement (cu. in.)
gear_ratio float %6.2f Gear Ratio
foreign byte %8.0g origin Car type
------------------------------------------------------------------------------------
Sorted by: foreign
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}
<<dd_do>>
assert mpg > 0 & mpg < 100
<</dd_do>>
~~~
<<dd_do: quietly>>
capture graph describe Graph
local checkdate = "`r(command_date)' `r(command_time)'"
<</dd_do>>
<<dd_skip_if: ="``gdate''"~="" & "``gdate''"=="`checkdate'">>
<<dd_graph>>
<<dd_skip_end>>
<<dd_do: quietly>>
local `gdate' = "`r(command_date)' `r(command_time)'"
<</dd_do>>
. 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:
<<dd_do>>
summarize weight
<</dd_do>>
This produces the following in the target HTML file:
. summarize weight
Variable | Obs Mean Std. Dev. Min Max
-------------+---------------------------------------------------------
weight | 74 3019.459 777.1936 1760 4840