---
title: Python Interpreter
slug: /python-interpreter
---
import Icon from "@site/src/components/icon";
import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';
This component allows you to execute Python code with imported packages.
The **Python Interpreter** component can only import packages that are already installed in your Langflow environment.
If you encounter an `ImportError` when trying to use a package, you need to install it first.
To install custom packages, see [Install custom dependencies](/install-custom-dependencies).
## Use the Python Interpreter in a flow
1. To use this component in a flow, in the **Global Imports** field, add the packages you want to import as a comma-separated list, such as `math,pandas`.
At least one import is required.
2. In the **Python Code** field, enter the Python code you want to execute. Use `print()` to see the output.
3. Optional: Enable **Tool Mode**, and then connect the **Python Interpreter** component to an **Agent** component as a tool.
For example, connect a **Python Interpreter** component and a [**Calculator** component](/calculator) as tools for an **Agent** component, and then test how it chooses different tools to solve math problems.
4. Ask the agent an easier math question.
The **Calculator** tool can add, subtract, multiple, divide, or perform exponentiation.
The agent executes the `evaluate_expression` tool to correctly answer the question.
Result:
```text
Executed evaluate_expression
Input:
{
"expression": "2+5"
}
Output:
{
"result": "7"
}
```
5. Give the agent complete Python code.
This example creates a Pandas DataFrame table with the imported `pandas` packages, and returns the square root of the mean squares.
```python
import pandas as pd
import math
# Create a simple DataFrame
df = pd.DataFrame({
'numbers': [1, 2, 3, 4, 5],
'squares': [x**2 for x in range(1, 6)]
})
# Calculate the square root of the mean
result = math.sqrt(df['squares'].mean())
print(f"Square root of mean squares: {result}")
```
The agent correctly chooses the `run_python_repl` tool to solve the problem.
Result:
```text
Executed run_python_repl
Input:
{
"python_code": "import pandas as pd\nimport math\n\n# Create a simple DataFrame\ndf = pd.DataFrame({\n 'numbers': [1, 2, 3, 4, 5],\n 'squares': [x**2 for x in range(1, 6)]\n})\n\n# Calculate the square root of the mean\nresult = math.sqrt(df['squares'].mean())\nprint(f\"Square root of mean squares: {result}\")"
}
Output:
{
"result": "Square root of mean squares: 3.3166247903554"
}
```
If you don't include the package imports in the chat, the agent can still create the table using `pd.DataFrame`, because the `pandas` package is imported globally by the **Python Interpreter** component in the **Global Imports** field.
## Pass inputs to the Python Interpreter
To pass inputs to the **Python Interpreter** component, you need to customize the component's code to add input fields.
After the input field is added to the component code, the port becomes available for connections.
For example, to connect a [**Text** component](/legacy-core-components) and pass a URL value to the **Python Interpreter** component, do the following:
1. Add a **Python Interpreter** component to your flow.
2. To modify the **Python Interpreter** component's code, click **Edit Code**.
3. To pass a URL input to the **Python Interpreter** component, make the following changes to the code:
a. Add the URL input field to the `inputs` list. This creates the input port that other components can connect to.
b. Update the `get_globals` method to extract the URL value and add it to the globals dictionary.
This makes the `url` variable available in the component's Python code.
c. Update the default Python code value to use the `url` variable.
The following example demonstrates these modifications.
Python code example
```python
import importlib
from langchain_experimental.utilities import PythonREPL
from lfx.custom.custom_component.component import Component
from lfx.io import MultilineInput, Output, StrInput
from lfx.schema.data import Data
from lfx.schema.message import Message # Needed to extract text from Message objects
class PythonREPLComponent(Component):
display_name = "Python Interpreter"
description = "Run Python code with optional imports. Use print() to see the output."
documentation: str = "https://docs.langflow.org/python-interpreter"
icon = "square-terminal"
inputs = [
StrInput(
name="global_imports",
display_name="Global Imports",
info="A comma-separated list of modules to import globally, e.g. 'math,numpy,pandas'.",
value="math,pandas",
required=True,
),
MultilineInput(
name="python_code",
display_name="Python Code",
info="The Python code to execute. Only modules specified in Global Imports can be used. Use 'url' variable if URL input is connected.",
value="print(f'URL: {url}')", # Updated to make the URL variable available to the Python code execution
input_types=["Message"],
tool_mode=True,
required=True,
),
# Add the URL input field to inputs list
StrInput(
name="url",
display_name="URL",
info="URL variable that can be used in Python code. Connect a Text component or enter manually.",
value="",
input_types=["Text", "Message"],
required=False,
),
]
outputs = [
Output(
display_name="Results",
name="results",
type_=Data,
method="run_python_repl",
),
]
def get_globals(self, global_imports: str | list[str]) -> dict:
"""Create a globals dictionary with only the specified allowed imports and input variables."""
global_dict = {}
try:
if isinstance(global_imports, str):
modules = [module.strip() for module in global_imports.split(",")]
elif isinstance(global_imports, list):
modules = global_imports
else:
msg = "global_imports must be either a string or a list"
raise TypeError(msg)
for module in modules:
try:
imported_module = importlib.import_module(module)
global_dict[imported_module.__name__] = imported_module
except ImportError as e:
msg = f"Could not import module {module}: {e!s}"
raise ImportError(msg) from e
# Add the URL variable to the component's globals dictionary
# Extract from Message object or use the string directly
if hasattr(self, "url") and self.url:
url_value = self.url.text if isinstance(self.url, Message) else str(self.url)
if url_value:
global_dict["url"] = url_value # Makes 'url' available in Python code
self.log(f"URL variable set: {url_value}")
except Exception as e:
self.log(f"Error in global imports: {e!s}")
raise
else:
self.log(f"Successfully imported modules: {list(global_dict.keys())}")
return global_dict
def run_python_repl(self) -> Data:
try:
# Extract Python code text if it's a Message object
python_code_text = self.python_code
if isinstance(python_code_text, Message):
python_code_text = python_code_text.text if python_code_text.text else ""
elif not isinstance(python_code_text, str):
python_code_text = str(python_code_text)
globals_ = self.get_globals(self.global_imports)
python_repl = PythonREPL(_globals=globals_)
result = python_repl.run(python_code_text)
result = result.strip() if result else ""
self.log("Code execution completed successfully")
return Data(data={"result": result})
except ImportError as e:
error_message = f"Import Error: {e!s}"
self.log(error_message)
return Data(data={"error": error_message})
except SyntaxError as e:
error_message = f"Syntax Error: {e!s}"
self.log(error_message)
return Data(data={"error": error_message})
except (NameError, TypeError, ValueError) as e:
error_message = f"Error during execution: {e!s}"
self.log(error_message)
return Data(data={"error": error_message})
def build(self):
return self.run_python_repl
```
4. To save the modifications, click **Check & Save**.
5. Add a **Text** component to your flow and set its value, such as `google.com`.
6. Connect the **Text** component's output to the new **URL** input field on your customized **Python Interpreter** component.
The **Python Interpreter** component can now use the `url` variable in the Python code that it executes.
## Python Interpreter parameters
| Name | Type | Description |
|------|------|-------------|
| global_imports | String | Input parameter. A comma-separated list of modules to import globally, such as `math,pandas,numpy`. |
| python_code | Code | Input parameter. The Python code to execute. Only modules specified in Global Imports can be used. |
| results | Data | Output parameter. The output of the executed Python code, including any printed results or errors. |