Struct Writer 

pub struct Writer { /* private fields */ }

Writer for TACO trajectory files

Implementations

impl Writer

pub fn create<P: AsRef<Path>>( path: P, num_atoms: u32, time_step: f64, simulation_metadata: SimulationMetadata, atom_metadata: AtomMetadata, compression_settings: CompressionSettings, ) -> Result<Self>

Create a new TACO writer

pub fn append<P: AsRef<Path>>(path: P) -> Result<Self>

Open an existing TACO file for appending frames

This method allows you to add more frames to an existing TACO trajectory file without rewriting the entire file. The append operation:

• Reads the existing file header and frame index
• Loads the last frame as the reference for delta encoding
• Positions the file pointer at the end of the frame data
• Allows writing new frames with proper delta encoding chain
• Updates the frame index and header when finish() is called

Important Notes

• The delta encoding chain is maintained by using the last existing frame as the reference for the first appended frame
• Full frame intervals are respected based on the total frame count
• All metadata (atom count, compression settings, etc.) is preserved
• The original frame index is overwritten when new frames are appended

Example

use taco_format::{Writer, Reader, Frame, FrameData, SimulationMetadata, AtomMetadata, CompressionSettings};
use ndarray::Array2;

// Create an initial trajectory file
let mut writer = Writer::create(
    "trajectory.taco",
    3,
    0.001,
    SimulationMetadata::default(),
    AtomMetadata::default(),
    CompressionSettings::default(),
)?;

// Write some initial frames
let positions = Array2::<f32>::zeros((3, 3));
for i in 0..10 {
    let frame = Frame::new(i, i as f64 * 0.001, FrameData::new(positions.clone()));
    writer.write_frame(frame)?;
}
writer.finish()?;

// Later, append more frames
let mut writer = Writer::append("trajectory.taco")?;
for i in 10..20 {
    let frame = Frame::new(i, i as f64 * 0.001, FrameData::new(positions.clone()));
    writer.write_frame(frame)?;
}
writer.finish()?;

// Verify we now have 20 frames
let reader = Reader::open("trajectory.taco")?;
assert_eq!(reader.num_frames(), 20);

Errors

Returns an error if:

• The file does not exist or cannot be opened
• The file is not a valid TACO format file
• The file is corrupted or has an invalid frame index

pub fn create_with_header<P: AsRef<Path>>( path: P, header: Header, ) -> Result<Self>

Create a new TACO writer with a custom header

pub fn write_frame(&mut self, frame: Frame) -> Result<()>

Write a single frame

pub fn write_frames(&mut self, frames: Vec<Frame>) -> Result<()>

Write multiple frames sequentially

pub fn finish(self) -> Result<()>

Finish writing the file, write the index and update the header