pyflange.utils

Internal utilities shared by the other PyFlange modules.

This module collects small helpers that are used throughout the library:

  • Logging helpers: Logger, log_data and read_data_log.
  • load_csv_database, which loads the tabular data (bolt dimensions, material properties, shell stiffness results, etc.) shipped with the package.
  • reduce_to_pi, an angle reduction function.

These helpers are mainly meant for internal use, but they are public and documented because they may be useful when extending the library.

Logger(id)

Create a logger configured with the PyFlange logging level.

Parameters:
  • id (str) –

    Name of the logger. By convention, the __name__ of the calling module.
Returns:
  • –

    logging.Logger: The logger registered under the given name, with its level set to the module-level LEVEL constant (logging.DEBUG by default).
Example 
from pyflange.utils import Logger

logger = Logger(__name__)
logger.warning("Something looks suspicious")

load_csv_database(db_name, index_col='id') cached

Load one of the CSV databases shipped with the package.

The files are read from the data folder of the package, as data/<db_name>.csv. Results are cached, so each database is read from disk only once.

Parameters:
  • db_name (str) –

    Name of the database, without the .csv extension (e.g. "bolts.metric_screws").

  • index_col (str | None, default: 'id' ) –

    Name of the column used as row index. Use None to keep the default integer index. Defaults to "id".
Returns:
  • –

    pandas.DataFrame: The database content. Since the result is cached, it should be treated as read-only.
Raises:
  • FileNotFoundError –

    If no database with the given name exists.

log_data(object, **kwargs)

Attach intermediate calculation values to an object.

The values are stored in a private dictionary on the object (created on first use), so that intermediate results of a calculation can be inspected afterwards with read_data_log. Existing keys are overwritten.

Parameters:
  • object (Any) –

    The object the data is attached to.

  • **kwargs –

    Named values to log.
Example 
from pyflange.utils import log_data, read_data_log

class Calc: pass
calc = Calc()
log_data(calc, k_shell=1.5e9, f_tot=2.0)
read_data_log(calc, "f_tot")    # 2.0

read_data_log(object, key)

Read a value previously stored with log_data.

Parameters:
  • object (Any) –

    The object the data was attached to.

  • key (str) –

    Name of the logged value.
Returns:
  • Any –

    The logged value, or None if nothing has been logged on the object or if the key is unknown.

reduce_to_pi(angle)

Reduce an angle to the interval [0, pi].

The angle is first wrapped to (-pi, pi] and then its absolute value is taken. This is useful for angles whose sign is irrelevant, such as a tilt angle magnitude.

Parameters:
  • angle (float) –

    The angle, in radians.
Returns:
  • float –

    The equivalent non-negative angle in radians, between 0 and pi.
Example 
from math import pi
reduce_to_pi(3*pi/2)    # pi/2
reduce_to_pi(-0.3)      # 0.3