# pyblp.options¶

Global options.

pyblp.options.digits

Number of digits displayed by status updates. The default number of digits is 7. The number of digits can be changed to, for example, 2, with pyblp.options.digits = 2.

Type

int

pyblp.options.verbose

Whether to output status updates. By default, verbosity is turned on. Verbosity can be turned off with pyblp.options.verbose = False.

Type

bool

pyblp.options.verbose_tracebacks

Whether to include full tracebacks in error messages. By default, full tracebacks are turned off. These can be useful when attempting to find the source of an error message. Tracebacks can be turned on with pyblp.options.verbose_tracebacks = True.

Type

bool

pyblp.options.verbose_output

Function used to output status updates. The default function is simply print. The function can be changed, for example, to include an indicator that statuses are from this package, with pyblp.verbose_output = lambda x: print(f"pyblp: {x}").

Type

callable

pyblp.options.flush_output

Whether to call sys.stdout.flush() after outputting a status update. By default, output is not flushed to standard output. To force standard output flushes after every status update, set pyblp.options.flush_output = True. This may be particularly desirable for R users who are calling PyBLP from reticulate <https://github.com/rstudio/reticulate>_, since standard output is typically not automatically flushed to the screen in this environment. If PyBLP is imported as pyblp, this setting can be enabled in R with pyblp$options$flush_output <- TRUE.

Type

bool

pyblp.options.dtype

The data type used for internal calculations, which is by default numpy.float64. The other recommended option is numpy.longdouble, which is the only extended precision floating point type currently supported by NumPy. Although this data type will be used internally, numpy.float64 will be used when passing arrays to optimization and fixed point routines, which may not support extended precision. The library underlying scipy.linalg, which is used for matrix inversion, may also use numpy.float64.

One instance in which extended precision can be helpful in the BLP problem is when there are a large number of near zero choice probabilities with small integration weights, which, under standard precision are called zeros when in aggregate they are nonzero. For example, Skrainka (2012) finds that using long doubles is sufficient to solve many utility floating point problems.

The precision of numpy.longdouble depends on the platform on which NumPy is installed. If the platform in use does not support extended precision, using numpy.longdouble may lead to unreliable results. For example, on Windows, NumPy is usually compiled such that numpy.longdouble often behaves like numpy.float64. Precisions can be compared with numpy.finfo by running numpy.finfo(numpy.float64) and numpy.finfo(numpy.longdouble). For more information, refer to this discussion.

If extended precisions is supported, the data type can be switched with pyblp.options.dtype = numpy.longdouble. On Windows, it is often easier to install Linux in a virtual machine than it is to build NumPy from source with a non-standard compiler.

Type

dtype

pyblp.options.finite_differences_epsilon

Perturbation $$\epsilon$$ used to numerically approximate derivatives with central finite differences:

(1)$f'(x) = \frac{f(x + \epsilon / 2) - f(x - \epsilon / 2)}{\epsilon}.$

By default, this is the square root of the machine epsilon: numpy.sqrt(numpy.finfo(options.dtype).eps). The typical example where this is used is when computing the Hessian, but it may also be used to compute Jacobians required for standard errors when analytic gradients are disabled.

Type

float

pyblp.options.pseudo_inverses

Whether to compute Moore-Penrose pseudo-inverses of matrices with scipy.linalg.pinv() instead of their classic inverses with scipy.linalg.inv(). This is by default True, so pseudo-inverses will be used. Up to small numerical differences, the pseudo-inverse is identical to the classic inverse for invertible matrices. Using the pseudo-inverse by default can help alleviate problems from, for example, near-singular weighting matrices.

To always attempt to compute classic inverses first, set pyblp.options.pseudo_inverses = False. If a classic inverse cannot be computed, an error will be displayed, and a pseudo-inverse may be computed instead.

Type

bool

pyblp.options.collinear_atol

Absolute tolerance for detecting collinear columns in each matrix of product characteristics and instruments: $$X_1$$, $$X_2$$, $$X_3$$, $$Z_D$$, and $$Z_S$$.

Each matrix is decomposed into a $$QR$$ decomposition and an error is raised for any column whose diagonal element in $$R$$ has a magnitude less than collinear_atol + collinear_rtol * sd where sd is the column’s standard deviation.

The default absolute tolerance is 1e-14. To disable collinearity checks, set pyblp.options.collinear_atol = pyblp.options.collinear_rtol = 0.

Type

float

pyblp.options.weights_tol

Tolerance for detecting integration weights that do not sum to one in each market, which is by default 1e-10. In most setups weights should essentially sum to one, but for example with importance sampling they may be slightly different. Warnings can be disabled by setting this to numpy.inf.

Type

float

pyblp.options.collinear_rtol

Relative tolerance for detecting collinear columns, which is by default also 1e-14.

Type

float

pyblp.options.psd_atol

Absolute tolerance for detecting non-positive semidefinite matrices. For example, this check is applied to any custom weighting matrix, $$W$$.

Singular value decomposition factorizes the matrix into $$U \Sigma V$$ and an error is raised if any element in the original matrix differs in absolute value from $$V' \Sigma V$$ by more than psd_atol + psd_rtol * abs where abs is the element’s absolute value.

The default tolerance is 1e-8. To disable positive semidefinite checks, set pyblp.options.psd_atol = pyblp.options.psd_rtol = numpy.inf.

Type

float

pyblp.options.psd_rtol

Relative tolerance for detecting non-positive definite matrices, which is by default also 1e-8`.

Type

float