Are you dealing with the Python nameerror: name ‘col’ is not defined while working in Pyspark?
If you’re struggling to fix the name ‘col’ is not defined, keep on reading!
This article discusses what this error means and will explore how to fix this error simply and effectively.
What is “nameerror name ‘col’ is not defined”?
The error message nameerror: name ‘col’ is not defined occurs when you are using the variable or function “col” without importing it first.
In simple words, this error message occurs when the “col” function is not imported or defined correctly.
In addition to that, it occurs when the PySpark interpreter cannot find the “col” function.
The “col” function is used to access a column in a PySpark dataframe.
What are the root causes of “nameerror: name ‘col’ is not defined”?
This error can occur because of several factors that includes the following:
❌ Missing import statement.
❌ Incorrect installation of the PySpark package.
❌Typo in the function name.
How to fix “nameerror: name ‘col’ is not defined”?
To fix this error, ensure that you have imported the “col” function correctly.
If you’re using PySpark, you can import the “col” function from pyspark.sql.functions by adding the line from pyspark.sql.functions import col at the beginning of your Python script
Here are the following solutions which you can use to fix this error.
Solution 1: Import “col” function
You have to import the “col” function from pyspark.sql.functions to use its function.
For example:
✅ from pyspark.sql.functions import col
Solution 2: Use alias for the col function
If you want to use another name for the “col” function, you can import it with an alias by using the following line at the top or beginning of your script.
For example:
✅ from pyspark.sql.functions import col as columnThis solution allows you to use the column function in your code instead of “col.”
3. Import all pyspark functions directly
You can also import all pyspark functions directly. However, import * is generally discouraged as it can lead you to unknown imports or overwrites.
For example:
from pyspark.sql.functions import *
add your code here>>
This line calls the col function 👇
col('my_column')On the other hand, you can also use an alias in order to solve function shadowing.
For example:
from pyspark.sql import functions as f
add your code here>>
This line calls the col function 👇
f.col('my_column')4. Use the fully qualified name for the col function
When you prefer not to import the “col” function, you can use its fully qualified name by using the following line at the top or beginning of your script.
For example:
✅ import pyspark.sql.functions as FAfter you import the “col” function, you can use the function in your code by calling it as F.col.
For example:
✅ df.select(F.col("column_name"))Conclusion
In conclusion, the error message nameerror: name ‘col’ is not defined occurs when you are using the variable or function “col” without importing it first.
This article discusses what this error is all about and already provides solutions to help you fix this error.
You could also check out other “nameerror” articles that may help you in the future if you encounter them.
- Nameerror: name ‘_c’ is not defined
- Nameerror name true is not defined
- Nameerror name keras is not defined
We are hoping that this article helps you fix the error. Thank you for reading itsourcecoders 😊
Frequently Asked Questions
What is Python NameError and what causes it?
NameError is raised when Python encounters a name (variable, function, class) that hasn’t been defined in the current scope. Most common causes: typo in variable name, using a variable before assigning it, missing import, or referencing a variable that was defined inside a function but accessed outside it.
How do I fix ‘name X is not defined’?
Check three things: (1) Is the name a typo? Compare with the spelling where you defined it. (2) Did you import it? Add ‘from module import X’ or ‘import module’ at the top. (3) Is X defined in a different scope (inside a function, conditional branch, or with-block) that hasn’t executed yet at the point you’re using it? Move the definition before the use.
Why does my variable work in one cell but not another (Jupyter)?
Jupyter kernels keep state between cells. If you defined X in cell 5 and run cell 3 later, X exists. But after Kernel-Restart, only the cells you re-run define their variables. Always run cells top-to-bottom on a fresh kernel before submitting. Use ‘Restart and Run All’ to verify your notebook is reproducible.
What is the difference between NameError and AttributeError?
NameError: the name itself doesn’t exist anywhere in scope (typo, missing import, scope issue). AttributeError: the name exists and points to an object, but that object has no such attribute/method (typo on method name, wrong object type). NameError is about the variable; AttributeError is about what’s inside it.
Where can I find more NameError fixes?
Browse the NameError reference hub for 49+ specific fixes (NumPy, pandas, Jupyter, Python 2 to 3 migration). For Python scope rules see the Python Tutorial hub. For attribute-level errors see AttributeError.
Caren Bautista
Technical Writer at PIES IT Solution
Responsible for crafting clear, well-structured, and beginner-friendly content across the platform. Handles the writing, proofreading, and editorial review of tutorials, guides, and documentation to ensure every article is accurate, readable, and easy to follow.
Expertise: Technical Writing · Content Creation · Documentation · Editorial Writing · JavaScript · TypeScript · Python · Python Errors · HTTP Errors · MS Excel · View all posts by Caren Bautista →