help reshape dialog: reshape
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Title
[D] reshape -- Convert data from wide to long form and vice versa
Syntax
Basic Syntax
reshape long stubnames, i(varlist) [options]
reshape wide stubnames, i(varlist) [options]
reshape error
long
+------------+ wide
| i j stub | +----------------+
|------------| | i stub1 stub2 |
| 1 1 4.1 | reshape |----------------|
| 1 2 4.5 | <---------> | 1 4.1 4.5 |
| 2 1 3.3 | | 2 3.3 3.0 |
| 2 2 3.0 | +----------------+
+------------+
To go from long to wide:
j existing variable
/
reshape wide stub, i(i) j(j)
To go from wide to long:
reshape long stub, i(i) j(j)
\
j new variable
To go back to long after using reshape wide:
reshape long
To go back to wide after using reshape long:
reshape wide
options description
------------------------------------------------------------------------
* i(varlist) use varlist as the ID variables
j(varname [values]) long->wide: varname, existing variable
wide->long: varname, new variable
optionally specify values to subset
varname
string varname is a string variable (default is
numeric)
------------------------------------------------------------------------
* i(varlist) is required.
where values is #[-#] [...] if varname is numeric
(default)
"string" ["string" ...] if varname is string
and where stubnames are variable names (long->wide), or stubs of
variable names (wide->long), and either way, may contain @, denoting
where j appears or is to appear in the name.
In the example above, when we wrote "reshape wide stub", we could
have written "reshape wide stub@" because j by default ends up as a
suffix. Had we written stu@b, then the wide variables would have
been named stu1b and stu2b.
Advanced syntax
reshape i varlist
reshape j varname [values] [, string]
reshape xij fvarnames [, atwl(chars)]
reshape xi [varlist]
reshape [query]
reshape clear
Menu
Data > Create or change data > Other variable-transformation commands >
Convert data between wide and long
Description
reshape converts data from wide to long form and vice versa.
Options
i(varlist) specifies the variables whose unique values denote a logical
observation. i() is required.
j(varname [values]) specifies the variable whose unique values denote a
subobservation. values lists the unique values to be used from
varname, which typically are not explicitly stated because reshape
will determine them automatically from the data.
string specifies that j() may contain string values.
atwl(chars), available only with the advanced syntax and not shown in the
dialog box, specifies that chars be substituted for the @ character
when converting the data from wide to long form.
Remarks
Before using reshape, you need to determine whether the data are in long
or wide form. You also must determine the logical observation (i) and
the subobservation (j) by which to organize the data. Suppose that you
had the following data, which could be organized in wide or long form as
follows:
(wide form)
i ....... x_ij ........
id sex inc80 inc81 inc82
-------------------------------
1 0 5000 5500 6000
2 1 2000 2200 3300
3 0 3000 2000 1000
(long form)
i j x_ij
id year sex inc
-----------------------
1 80 0 5000
1 81 0 5500
1 82 0 6000
2 80 1 2000
2 81 1 2200
2 82 1 3300
3 80 0 3000
3 81 0 2000
3 82 0 1000
Given these data, you could use reshape to convert from one form to the
other:
. reshape long inc, i(id) j(year) (goes from top form to bottom)
. reshape wide inc, i(id) j(year) (goes from bottom form to top)
See [D] reshape for a detailed discussion and examples for both the basic
and advanced syntax.
Examples
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Setup
. webuse reshape1
List the data
. list
Convert data from wide form to long form
. reshape long inc ue, i(id) j(year)
List the result
. list, sepby(id)
Convert data back from long form to wide form (quick way)
. reshape wide
Convert data back from long form to wide form (explicit way)
. reshape wide inc ue, i(id) j(year)
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Setup
. webuse reshape2, clear
List the data
. list
Try to convert the data from wide form to long form
. reshape long inc, i(id) j(year)
List the problem observations
. reshape error
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Setup
. webuse reshape3, clear
List the data
. list
Convert the data from wide form to long form
. reshape long inc@r ue, i(id) j(year)
List the result
. list, sepby(id)
Convert the data back from long form to wide form (quick way)
. reshape wide
Convert the data back from long form to wide form (explicit way)
. reshape wide inc@r ue, i(id) j(year)
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Setup
. webuse reshape4, clear
List the data
. list
Convert the data from wide form to long form, allowing sex to take on
string values
. reshape long inc, i(id) j(sex) string
List the result
. list, sepby(id)
Convert the data back from long form to wide form (quick way)
. reshape wide
Convert the data back from long form to wide form (explicit way)
. reshape wide inc, i(id) j(sex) string
---------------------------------------------------------------------------
Setup
. webuse reshape5, clear
List the data
. list
Convert the data from long-long form to wide-wide form (two j variables)
. reshape wide @inc, i(hid year) j(sex) string
. reshape wide minc finc, i(hid) j(year)
List the result
. list
Convert the data back from wide-wide form to long-long form
. reshape long minc finc, i(hid) j(year)
. reshape long @inc, i(hid year) j(sex) string
List the result
. list
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Saved results
reshape stores the following characteristics with the data (see [P]
char):
_dta[ReS_i] i variable names
_dta[ReS_j] j variable name
_dta[ReS_jv] j values, if specified
_dta[ReS_Xij] X_ij variable names
_dta[ReS_Xi] X_i variable names, if specified
_dta[ReS_atwl] atwl() value, if specified
_dta[ReS_str] 1 if option string specified; 0 otherwise
Also see
Manual: [D] reshape
Help: [P] char, [D] save, [D] stack, [D] xpose
