Stata batch renaming, data checking, row and column conversion, type conversion, variable interception and generation, database merging and other commands _stata

One, variable batch renaming:

For example, to change the number of variables a_2 b_2 c_2 d_2 e_2 suffix to W

ren (*_2) (*W)

Second, check the duplicate data commonly used commands:

Duplicates report X//Reports x variable has no duplicates

Duplicates list x//list duplicate records

Bys X:gen Cn=_n

Browse if Cn>1

Drop CN//Browse specific duplicate values for next step analysis and processing

Duplicates drop x//delete duplicate value, keep first record of duplicate value

Third, the data transverse longitudinal conversion:
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 | +----------------+
+------------+

Reshape before checking j,stub have duplicate records, there is no repetition can not reshape.

Turn vertically to landscape--if J is a Chinese character, first rename the variable to the English letter (RT) or the number can be beats after the variable name:

Gen rt= "BP" if j== "blood pressure"

Replace rt= ' height ' if j== ' height '

Reshape wide all the same I correspond to an inconsistent variable, I () j () string//If J is string, followed by a string tag

Transverse to portrait--to name the horizontal data as Stub1 stub2 and so on, to generate a new J variable.

Reshape long stub, I () j (new variable name)

Iv. data type conversions: destring, replace force

ToString, replace force

V. Intercept the generation of new variables: for example blood pressure (BP) 130/85 interception for high pressure (SBP) and low pressure (DBP)

Gen Sbp=real (substr (bp,1,3))

Gen Dbp=real (substr (bp,-2,2))

Calculate a new variable: for example, calculate BMI with height and weight data

Gen Bmi=weight^10000/(height^2)//weight multiplied by 10,000 divided by the square of height

Vii. Consolidation of databases:

Merge: Add new variable append: variable unchanged, add record

The variables used by the merge 1:1/1:m/m:1 barcode using "FILE.DTA"//merge must not be duplicated, and must be processed first

Append using filename

Calculate the same number of records in the variable x:

For example, the variable x represents the medical number, there are several identical medical numbers on behalf of this person a few times, now to screen out more than three times the number of people

Gen N=_n

by Tjid, Sort:gen n1=_n//N1 represents how many observations each tijd has

Drop if N1 <=3 or keep if N1 >=3