tecio.open

tecio.open(path, mode='r', **kwargs)

Open a Tecplot file for reading, writing, or appending.

Selects the correct format handler from the file extension and returns the appropriate reader or writer. All handles are context managers.

Parameters:

• path (str | os.PathLike) – File path. Extension determines the format handler:

  • .szplt → tecio.szl

  • .plt / .bin → tecio.plt

  • .dat / .tec → tecio.dat

• mode (str) – Access mode — mirrors Python’s built-in open():

  • 'r' – Open Tecplot file for reading.

  • 'w' – Open Tecplot file for writing, truncating the file first.

  • 'x' – Open Tecplot file for exclusive creation, failing if the file already exists.

  • 'a' – Append new zones to an existing file. The file is stream-copied to a temporary file; on close the temporary atomically replaces the original. Raises FileNotFoundError if the file does not exist (use 'w' to create a new file).

  • 'a+' – Same as 'a' but the returned handle also exposes the full read API populated from the original file.

• **kwargs – Forwarded to the underlying handler constructor. The accepted keyword arguments differ by mode — see the tables below.

Keyword Args (modes 'r', 'w', 'x'):

Forwarded directly to the format’s Read or Write constructor.

For reading — no keyword arguments are accepted; all metadata is read from the file.

For writing ('w' and 'x'):

Keyword	Default	Description
title	""	Dataset title string embedded in the file header.
variables	None	Variable name list. For SZL and PLT this may be deferred to the first write_ijk_zone() or write_fe_zone() call. Required at open time for DAT.
file_type	FileType.FULL	One of FULL, GRID, or SOLUTION.

Keyword Args (modes 'a', 'a+'):

title, variables, and file_type default to the values read from the existing file. In most cases you should not pass these — they are documented here for completeness.

Keyword	Default	Description
title	From file	Override the dataset title in the output file. Rarely needed — the existing title is preserved by default.
variables	From file	Do not override. The variable list is fixed by the existing file. Passing a different list will cause a mismatch between the copied zones and any new zones.
file_type	From file	Override the file type. Rarely needed.

Returns:

• 'r' → tecio.szl.Read, tecio.plt.Read, or tecio.dat.Read

• 'w' / 'x' → tecio.szl.Write, tecio.plt.Write, or tecio.dat.Write

• 'a' → AppendWrite

• 'a+' → AppendReadWrite

Raises:

• ValueError – Unsupported file extension or unrecognised mode.

• FileNotFoundError – 'r', 'a', or 'a+' on a missing file.

• FileExistsError – 'x' on an existing file.

• NotImplementedError – Append mode on a file containing FEPOLYGON or FEPOLYHEDRON zones.

Examples

Read a file:

>>> with tecio.open("flow.szplt") as tec:
...     x = tec.zone[0].variable["x"].values

Write a new file, deferring variable names to the first zone:

>>> with tecio.open("out.szplt", "w", title="Run 1") as tec:
...     tec.write_ijk_zone(data=[x, y, p], variables=["x", "y", "p"])

Append a new zone to an existing file:

>>> with tecio.open("out.szplt", "a") as tec:
...     tec.write_ijk_zone(data=[x2, y2, p2], solution_time=2.0)

Append and read in the same session:

>>> with tecio.open("out.szplt", "a+") as tec:
...     prev_p = tec.zone[-1].variable["p"].values
...     tec.write_ijk_zone(data=[x2, y2, prev_p * 0.9])