Preserve and restore commands in STATA offers invaluable help, especially working with large data sets. Suppose you are working on a data set and for some purposes, you have altered the data set but now you want to retrieve the original data set and run operations on it. you can do that by using simple operations in STATA. To understand the procedure, follow the below procedure.
Upload the data set into STATA. We are using the inbuilt dataset and the syntax for using such data is
sysuse auto.dta,clear
Now, we will alter the data by using the following commands:
collapse (mean) price mpg weight, by(foreign)
Related Article: Aggregate Data by Group using Collapse command in Stata
By doing so our original data set has been altered and the output window will only display the following outputs
Since our original data has been changed and we are not able to perform any operations on the original data set. That’s where the preserve command helps us. The preserve command helps us to retrieve the original data set even after altering the data set. While working with preserve command it must be kept in mind that it needs to be run simultaneously with other operations.
sysuse auto.dta,clear preserve collapse (mean) price mpg weight, by(foreign) list in 1/2
By running the above commands we will get the below output.
Observe that, in the above picture output window, the initial data set has been preserved but at the same time, we have achieved the mean value of price, mpg, and weight.
Similarly, the restore command can also help us to restore our original data set even if the data is being altered. To do so follow the commands:
sysuse auto.dta,clear preserve drop price mpg
By running this command, the variable price has been dropped. We can restore the original data set by using the restore command.
restore
In the below example, we will explicitly employ the restore command to help us. First, upload the data set
sysuser auto.dta,clear
Now, we will preserve the data set by employing the preserve command
preserve collapse (mean) price mpg weight, by(foreign) restore list in 1/2
This result shows the original data set.
