Working with Stata Files in Python: Reading Variable Labels with Pandas

In this article, we make ourselves familiar with one more file type the Stata files in Python which come with several extensions(.dta,.ado,.do,.smcl, etc explained below). We also look at different methods to return a dictionary associating each variable name with the corresponding label.

Understanding Stata Files

Academic and research communities widely use Stata software a statistical analysis and data management tool, the files used by this software are Stata files. A more interesting fact about Stata files is that they come in several formats including .data(data files), .ado(program files), .do(command files), .smcl(log files), and others. We have used .dta files below as it is the most commonly used since it stores data in a proprietary binary format that is optimized for use with management features.

As mentioned before academic and research communities use this widely for one main reason stata files can store data from various sources such as surveys, experiments, and administrative records in a structured and organized manner. They store information about variables such as their names, labels, and data types with that it stores value about data values such as their formats, missing values, and value labels.

Creating a Stata File with Pandas

To read variable labels from Stata files in Python, you can use the Pandas library along with the StataReader module. There are three methods to accomplish this: 1) Using StataReader and variable_labels() method, 2) Importing StataReader directly, and 3) Using Pandas read_stata with an iterator. By retrieving variable labels, you can easily identify and understand the purpose of each variable in your dataset, which is especially useful when working with large datasets containing many variables.

Below is a code snippet to create a Stata file

import pandas as pd
data = pd.DataFrame({'var1': [1, 2, 3], 'var2': ['a', 'b', 'c']})

# input the path where you want to store the stata file
data.to_stata(r'C:/path/file.dta')
print(data)

We create 3 rows and 2 columns /labels.

Expected Output

Method 1: Using StataReader and variable_labels()

The StataReader class is used to read the content of a Stata file and the variable_labels() method is called on the StataReader object to extract the variable labels.

import pandas as pd
from pandas.io.stata import StataReader

#  input the path where you want to store the stata file
data = StataReader(r'C:/path/file.dta')

var_labels = data.variable_labels()
print(var_labels)

The above block of code uses pandas with its alias pd and StataReader modules to read a Stata data file located at the specified path . To create a reader object which can read the content of a Stata file we use the StataReader module. The var_labels variable stores the variable labels of the file which are extracted via variable_labels() after that, we print the labels as a result

Output:

Method 2: Importing StataReader Directly

Here, the StataReader class is imported directly from the pandas.io.stata module, and the variable_labels() method is used to extract the variable labels from the StataReader object.

from pandas.io.stata import StataReader

stata_reader = StataReader('file.dta')

variable_labels = stata_reader.variable_labels()

print(variable_labels)

This code generates an instance of the StataReader class called stata_reader by importing the StataReader class from the pandas.io.stata module. It loads the “file.dta” Stata file into the stata_reader object.

The variable variable_labels() is then created by the code, and it uses the variable_labels() method to get the variable labels from the stata_reader object.

Output:

Method 3: Using Pandas read_stata with an Iterator

The iterator object allows reading the data in small chunks, which is useful for large datasets, and the variable_labels() method is called on the iterator to obtain the variable labels.

import pandas as pd

# Create an iterator to read the Stata file
iterator = pd.read_stata('file.dta', iterator=True)

variable_labels = iterator.variable_labels()

print(variable_labels)

This code imports the pandas library and reads a Stata file called file.dta using read_stata() method with the iterator parameter set to true.This will enable to creation an iterator object that can read data in small chunks rather than reading the entire file into memory. variable_labels variable stores the variable labels of the file which are extracted via variable_labels() after that, we print the labels as a result.

Output:

Conclusion

In this article, we explored three methods to read variable labels from Stata files in Python using the Pandas library and StataReader module. Retrieving variable labels is beneficial when working with large datasets containing numerous variables, as it helps in quickly identifying and understanding each variable’s purpose.

This technique can be used when exporting data from Stata files to other formats, such as CSV or SQL databases, by including variable labels as column headers for better comprehension. What other applications can you think of for reading variable labels from Stata files in Python?