…, then average

FIX: add working support for computation of multiple connectivity metrics at once, as indicated by existing docstring

FIX: correct calculation of PLV and coherence connectivity metrics

FIX: block_size parameter now actually corresponds to the size of blocks instead of number of blocks

ENH: add PLI and wPLI connectivity metrics

ENH: improve docstring and typechecks in code

ENH: streamline the public API with mne_connectivity.spectral_connectivity_epochs

ENH: enable averaging connectivity results over frequencies and epochs

…requency.tfr_array_multitaper

Co-authored-by: Adam Li <adam2392@gmail.com>

Co-authored-by: Adam Li <adam2392@gmail.com>

Co-authored-by: Adam Li <adam2392@gmail.com>

…putation may be None

Co-authored-by: Britta Westner <britta.wstnr@gmail.com>

Co-authored-by: Britta Westner <britta.wstnr@gmail.com>

…nto spectral_time_hypyp

…specified indices when set

This change will minimize memory usage by default.

Add a short description for the block_size parameter to allow users to
better understand the memory usage of the spectral_connectivity_time
function.

Improve the readability of code by shortening variable names in
pairwise_pli.

Remove the regression test which tests against the spectral connectivity
 implementation in frites. The implementation in frites is erroneous,
 and therefore we should not test against it.

The block_size parameter is not useful, as testing shows that running
the computation in blocks of epochs does not have a meaningful effect on
 the speed of computation, but significantly increases memory usage.

Added a note on memory mapping in the docstring of
spectral_connectivity_time. Corrected some typos and inconsistent
backticks.

Removed redundant comments, clarified and fixed typos.

…nto spectral_connectivity_time_pairwise

Co-authored-by: Adam Li <adam2392@gmail.com>

Co-authored-by: Adam Li <adam2392@gmail.com>

Co-authored-by: Adam Li <adam2392@gmail.com>

Add clear reference to MNE-Python functions.

Co-authored-by: Adam Li <adam2392@gmail.com>

Add some comments to clarify the new test case for time-resolved
spectral connectivity.

…nto spectral_connectivity_time_pairwise

Co-authored-by: Adam Li <adam2392@gmail.com>

Co-authored-by: Adam Li <adam2392@gmail.com>

Co-authored-by: Adam Li <adam2392@gmail.com>

Revised documentation of spectral_connectivity_time.

Spectral connectivity computation failed if cwt_freqs was only a single
number or an array with a single entry due to invalid array slicing.

Fixed by incrementing the upper bound of the slice by one when
computing the average in a frequency band.

Compute a weighted average of the tapered cross spectra when using
the multitaper mode. Weighting is
derived from the concentration ratios between the DPSS windows.

Made the docstring more stylish, removed unnecessary things and
added better compliance with MNE-Python style guidelines.

The _spectral_connectivity function doesn't need defaults as these are
already spelled out in the main spectral_connectivity_time function
signature.