Stata 15 help for append

[D] append -- Append datasets


append using filename [filename ...] [, options]

You may enclose filename in double quotes and must do so if filename contains blanks or other special characters.

options Description ------------------------------------------------------------------------- generate(newvar) newvar marks source of resulting observations keep(varlist) keep specified variables from appending dataset(s) nolabel do not copy value-label definitions from dataset(s) on disk nonotes do not copy notes from dataset(s) on disk force append string to numeric or numeric to string without error -------------------------------------------------------------------------


Data > Combine datasets > Append datasets


append appends Stata-format datasets stored on disk to the end of the dataset in memory. If any filename is specified without an extension, .dta is assumed.

Stata can also join observations from two datasets into one; see [D] merge. See [U] 22 Combining datasets for a comparison of append, merge, and joinby.


generate(newvar) specifies the name of a variable to be created that will mark the source of observations. Observations from the master dataset (the data in memory before the append command) will contain 0 for this variable. Observations from the first using dataset will contain 1 for this variable; observations from the second using dataset will contain 2 for this variable; and so on.

keep(varlist) specifies the variables to be kept from the using dataset. If keep() is not specified, all variables are kept.

The varlist in keep(varlist) differs from standard Stata varlists in two ways: variable names in varlist may not be abbreviated, except by the use of wildcard characters, and you may not refer to a range of variables, such as price-weight.

nolabel prevents Stata from copying the value-label definitions from the disk dataset into the dataset in memory. Even if you do not specify this option, label definitions from the disk dataset never replace definitions already in memory.

nonotes prevents notes in the using dataset from being incorporated into the result. The default is to incorporate notes from the using dataset that do not already appear in the master data.

force allows string variables to be appended to numeric variables and vice versa, resulting in missing values from the using dataset. If omitted, append issues an error message; if specified, append issues a warning message.


--------------------------------------------------------------------------- Setup . webuse even . list . webuse odd . list

Append even data to the end of the odd data . append using

List the results . list

--------------------------------------------------------------------------- Setup . sysuse auto, clear . keep if foreign == 0 . save domestic . sysuse auto, clear . keep if foreign == 1 . keep make price mpg rep78 foreign

Append domestic car data to the end of the foreign car data and only keep variables make, price, mpg, rep78, and foreign from domestic car data . append using domestic, keep(make price mpg rep78 foreign)

List the results . list

--------------------------------------------------------------------------- Setup . sysuse citytemp, clear . keep if region == 4 . save west . sysuse citytemp, clear . keep if region == 3 . save south . sysuse citytemp, clear . keep if region == 1

Append temperature data for the West region (region==4) and the South region (region==3) to the end of the data for the New England region (region==1), and generate new variable filenum to indicate from which file each observation came. Do not load value-label definitions from west.dta or south.dta. . append using west south, generate(filenum) nolabel

List the results . list


Video example

How to append files into a single dataset

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