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Transition

polars_ts.imaging.transition

Markov Transition Field (MTF) imaging for time series.

Discretises values into quantile bins, estimates a Markov transition matrix, and maps transition probabilities back onto the time axis.

_quantile_bins(x, n_bins)

Assign each value to a quantile bin (0 to n_bins-1).

_mtf_matrix(x, n_bins, image_size)

Compute MTF for a single 1D series.

to_mtf(df, n_bins=8, image_size=None, id_col='unique_id', target_col='y')

Convert time series to Markov Transition Field images.

Quantises values into n_bins bins, computes the Markov transition matrix, then builds an n x n image where pixel (i, j) is the transition probability from bin(x_i) to bin(x_j).

Parameters

df DataFrame with columns id_col and target_col. n_bins Number of quantile bins for discretisation. image_size Output image dimension. None for full resolution (n x n). Smaller values use Piecewise Aggregate Approximation (PAA). id_col Column identifying each time series. target_col Column with the time series values.

Returns

dict[str, np.ndarray] Mapping from series ID to a square 2D array with values in [0, 1].