diff --git a/pyqtgraph/functions.py b/pyqtgraph/functions.py index e47aa411..75318bbc 100644 --- a/pyqtgraph/functions.py +++ b/pyqtgraph/functions.py @@ -2322,14 +2322,62 @@ def invertQTransform(tr): raise Exception("Transform is not invertible.") return inv[0] + +def pseudoScatter(data, spacing=None, shuffle=True, bidir=False, method='exact'): + """Return an array of position values needed to make beeswarm or column scatter plots. -def pseudoScatter(data, spacing=None, shuffle=True, bidir=False): - """ - Used for examining the distribution of values in a set. Produces scattering as in beeswarm or column scatter plots. + Used for examining the distribution of values in an array. - Given a list of x-values, construct a set of y-values such that an x,y scatter-plot + Given an array of x-values, construct an array of y-values such that an x,y scatter-plot will not have overlapping points (it will look similar to a histogram). """ + if method == 'exact': + return _pseudoScatterExact(data, spacing=spacing, shuffle=shuffle, bidir=bidir) + elif method == 'histogram': + return _pseudoScatterHistogram(data, spacing=spacing, shuffle=shuffle, bidir=bidir) + + +def _pseudoScatterHistogram(data, spacing=None, shuffle=True, bidir=False): + """Works by binning points into a histogram and spreading them out to fill the bin. + + Faster method, but can produce blocky results. + """ + inds = np.arange(len(data)) + if shuffle: + np.random.shuffle(inds) + + data = data[inds] + + if spacing is None: + spacing = 2.*np.std(data)/len(data)**0.5 + + yvals = np.empty(len(data)) + + dmin = data.min() + dmax = data.max() + nbins = int((dmax-dmin) / spacing) + 1 + bins = np.linspace(dmin, dmax, nbins) + dx = bins[1] - bins[0] + dbins = ((data - bins[0]) / dx).astype(int) + binCounts = {} + + for i,j in enumerate(dbins): + c = binCounts.get(j, -1) + 1 + binCounts[j] = c + yvals[i] = c + + if bidir is True: + for i in range(nbins): + yvals[dbins==i] -= binCounts.get(i, 0) * 0.5 + + return yvals[np.argsort(inds)] ## un-shuffle values before returning + + +def _pseudoScatterExact(data, spacing=None, shuffle=True, bidir=False): + """Works by stacking points up one at a time, searching for the lowest position available at each point. + + This method produces nice, smooth results but can be prohibitively slow for large datasets. + """ inds = np.arange(len(data)) if shuffle: np.random.shuffle(inds)