Skip to content

perf: use Polars streaming engine for LP file writing #563

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Closed
FBumann wants to merge 2 commits into from
Closed

perf: use Polars streaming engine for LP file writing #563

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
86232e8
perf: use Polars streaming engine for LP file writing
FBumann Jan 31, 2026
1d4b725
fix: log warning with traceback when Polars streaming fallback triggers
FBumann Jan 31, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
68 changes: 35 additions & 33 deletions linopy/io.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -54,6 +54,34 @@ def clean_name(name: str) -> str:
coord_sanitizer = str.maketrans("[,]", "(,)", " ")


def _format_and_write(
df: pl.DataFrame, columns: list[pl.Expr], f: BufferedWriter
) -> None:
"""
Format columns via concat_str and write to file.

Uses Polars streaming engine for better performance when available,
with automatic fallback to eager evaluation.
"""
kwargs: Any = dict(
separator=" ", null_value="", quote_style="never", include_header=False
)
try:
formatted = (
df.lazy()
.select(pl.concat_str(columns, ignore_nulls=True))
.collect(engine="streaming")
)
except Exception:
logger.warning(
"Polars streaming engine failed, falling back to eager evaluation. "
"Please report this at https://github.com/PyPSA/linopy/issues",
exc_info=True,
)
formatted = df.select(pl.concat_str(columns, ignore_nulls=True))
formatted.write_csv(f, **kwargs)


def signed_number(expr: pl.Expr) -> tuple[pl.Expr, pl.Expr]:
"""
Return polars expressions for a signed number string, handling -0.0 correctly.
Expand Down Expand Up @@ -155,10 +183,7 @@ def objective_write_linear_terms(
*signed_number(pl.col("coeffs")),
*print_variable(pl.col("vars")),
]
df = df.select(pl.concat_str(cols, ignore_nulls=True))
df.write_csv(
f, separator=" ", null_value="", quote_style="never", include_header=False
)
_format_and_write(df, cols, f)


def objective_write_quadratic_terms(
Expand All @@ -171,10 +196,7 @@ def objective_write_quadratic_terms(
*print_variable(pl.col("vars2")),
]
f.write(b"+ [\n")
df = df.select(pl.concat_str(cols, ignore_nulls=True))
df.write_csv(
f, separator=" ", null_value="", quote_style="never", include_header=False
)
_format_and_write(df, cols, f)
f.write(b"] / 2\n")


Expand Down Expand Up @@ -254,11 +276,7 @@ def bounds_to_file(
*signed_number(pl.col("upper")),
]

kwargs: Any = dict(
separator=" ", null_value="", quote_style="never", include_header=False
)
formatted = df.select(pl.concat_str(columns, ignore_nulls=True))
formatted.write_csv(f, **kwargs)
_format_and_write(df, columns, f)


def binaries_to_file(
Expand Down Expand Up @@ -296,11 +314,7 @@ def binaries_to_file(
*print_variable(pl.col("labels")),
]

kwargs: Any = dict(
separator=" ", null_value="", quote_style="never", include_header=False
)
formatted = df.select(pl.concat_str(columns, ignore_nulls=True))
formatted.write_csv(f, **kwargs)
_format_and_write(df, columns, f)


def integers_to_file(
Expand Down Expand Up @@ -339,11 +353,7 @@ def integers_to_file(
*print_variable(pl.col("labels")),
]

kwargs: Any = dict(
separator=" ", null_value="", quote_style="never", include_header=False
)
formatted = df.select(pl.concat_str(columns, ignore_nulls=True))
formatted.write_csv(f, **kwargs)
_format_and_write(df, columns, f)


def sos_to_file(
Expand Down Expand Up @@ -399,11 +409,7 @@ def sos_to_file(
pl.col("var_weights"),
]

kwargs: Any = dict(
separator=" ", null_value="", quote_style="never", include_header=False
)
formatted = df.select(pl.concat_str(columns, ignore_nulls=True))
formatted.write_csv(f, **kwargs)
_format_and_write(df, columns, f)


def constraints_to_file(
Expand Down Expand Up @@ -487,11 +493,7 @@ def constraints_to_file(
pl.when(pl.col("is_last_in_group")).then(pl.col("rhs").cast(pl.String)),
]

kwargs: Any = dict(
separator=" ", null_value="", quote_style="never", include_header=False
)
formatted = df.select(pl.concat_str(columns, ignore_nulls=True))
formatted.write_csv(f, **kwargs)
_format_and_write(df, columns, f)

# in the future, we could use lazy dataframes when they support appending
# tp existent files
Expand Down