CASTEP Input File Parser/Writer

0.1.11 verified Mon Apr 27 auth: no python

A simple Python library for parsing and writing CASTEP input (.cell, .param) files. Current version 0.1.11, release cadence irregular.

pip install castepinput

Common errors

error TypeError: argument of type 'CastepInput' is not iterable ↓

cause Trying to iterate over a CastepInput object directly; blocks must be accessed via .blocks attribute.

fix

Use cell.blocks.items() to iterate over blocks and their values.

error AttributeError: 'str' object has no attribute 'keys' ↓

cause Passing a file path string to CastepInput constructor instead of file content.

fix

Read the file content with open('file.cell').read() before passing to CastepInput.

Warnings

gotcha CastepInput accepts file content as a string, not a file path. Use open().read() to pass content. ↓

fix Read the file first: with open('path.cell') as f: content = f.read() then CastepInput(content)

gotcha Block values are stored as lists of lists; modifying direct list may not update the internal representation. Use the provided methods if available. ↓

fix Assign directly to `cell.blocks['blockname'] = new_list_of_lists`

Imports

CastepInput
wrong
```
from castepinput import CastepInputFile
```
correct
```
from castepinput import CastepInput
```
Common mistake: using CastepInputFile, correct class is CastepInput.
write_cell
```
from castepinput import write_cell
```
No common wrong import.

Quickstart

Read a .cell file, modify a block, and write it back.

from castepinput import CastepInput

# Parse an existing .cell file
with open('example.cell', 'r') as f:
    content = f.read()
cell = CastepInput(content)
print(cell.blocks)  # dict of blocks

# Modify and write back
cell.blocks['blockname'] = [['value1', 'value2']]
with open('output.cell', 'w') as f:
    f.write(str(cell))