# cytoflow.operations.flowpeaks¶

class cytoflow.operations.flowpeaks.FlowPeaksOp[source]

This module uses the flowPeaks algorithm to assign events to clusters in an unsupervised manner.

Call estimate() to compute the clusters.

Calling apply() creates a new categorical metadata variable named name, with possible values {name}_1 …. name_n where n is the number of clusters estimated.

The same model may not be appropriate for different subsets of the data set. If this is the case, you can use the by attribute to specify metadata by which to aggregate the data before estimating (and applying) a model. The number of clusters is a model parameter and it may vary in each subset.

name

The operation name; determines the name of the new metadata column

Type: Str
channels

The channels to apply the clustering algorithm to.

Type: List(Str)
scale

Re-scale the data in the specified channels before fitting. If a channel is in channels but not in scale, the current package-wide default (set with set_default_scale()) is used.

Type: Dict(Str : Enum(“linear”, “logicle”, “log”))
by

A list of metadata attributes to aggregate the data before estimating the model. For example, if the experiment has two pieces of metadata, Time and Dox, setting by = ["Time", "Dox"] will fit the model separately to each subset of the data with a unique combination of Time and Dox.

Type: List(Str)
h

A scalar value by which to scale the covariance matrices of the underlying density function. (See Notes, below, for more details.)

Type: Float (default = 1.5)
h0

A scalar value by which to smooth the covariance matrices of the underlying density function. (See Notes, below, for more details.)

Type: Float (default = 1.0)
tol

How readily should clusters be merged? Must be between 0 and 1. See Notes, below, for more details.

Type: Float (default = 0.5)
merge_dist

How far apart can clusters be before they are merged? This is a unit-free scalar, and is approximately the maximum number of k-means clusters between peaks.

Type: Float (default = 5)
find_outliers

Should the algorithm use an extra step to identify outliers?

Note

I have disabled this code until I can try to make it faster.

Type: Bool (default = False)

Notes

This algorithm uses kmeans to find a large number of clusters, then hierarchically merges those clusters. Thus, the user does not need to specify the number of clusters in advance, and it can find non-convex clusters. It also operates in an arbitrary number of dimensions.

The merging happens in two steps. First, the cluster centroids are used to estimate an underlying density function. Then, the local maxima of the density function are found using a numerical optimization starting from each centroid, and k-means clusters that converge to the same local maximum are merged. Finally, these clusters-of-clusters are merged if their local maxima are (a) close enough, and (b) the density function between them is smooth enough. Thus, the final assignment of each event depends on the k-means cluster it ends up in, and which cluster-of-clusters that k-means centroid is assigned to.

There are a lot of parameters that affect this process. The k-means clustering is pretty robust (though somewhat sensitive to the number of clusters, which is currently not exposed in the API.) The most important are exposed as attributes of the FlowPeaksOp class. These include:

• tol: How smooth does the density function have to be between two
density maxima to merge them? Must be between 0 and 1.
• merge_dist: How close must two maxima be to merge them? This
value is a unit-free scalar, and is approximately the number of k-means clusters between the two maxima.

For details and a theoretical justification, see [1]

References

 [1] Ge, Yongchao and Sealfon, Stuart C. “flowPeaks: a fast unsupervised clustering for flow cytometry data via K-means and density peak finding” Bioinformatics (2012) 28 (15): 2052-2058.

Examples

Make a little data set.

>>> import cytoflow as flow
>>> import_op = flow.ImportOp()
>>> import_op.tubes = [flow.Tube(file = "Plate01/RFP_Well_A3.fcs",
...                              conditions = {'Dox' : 10.0}),
...                    flow.Tube(file = "Plate01/CFP_Well_A4.fcs",
...                              conditions = {'Dox' : 1.0})]
>>> import_op.conditions = {'Dox' : 'float'}
>>> ex = import_op.apply()


Create and parameterize the operation.

>>> fp_op = flow.FlowPeaksOp(name = 'Flow',
...                          channels = ['V2-A', 'Y2-A'],
...                          scale = {'V2-A' : 'log',
...                                   'Y2-A' : 'log'},
...                          h0 = 3)


Estimate the clusters

>>> fp_op.estimate(ex)


Plot a diagnostic view of the underlying density

>>> fp_op.default_view(density = True).plot(ex)


Apply the gate

>>> ex2 = fp_op.apply(ex)


Plot a diagnostic view with the event assignments

>>> fp_op.default_view().plot(ex2)

estimate(experiment, subset=None)[source]

Estimate the k-means clusters, then hierarchically merge them.

Parameters: experiment (Experiment) – The Experiment to use to estimate the k-means clusters subset (str (default = None)) – A Python expression that specifies a subset of the data in experiment to use to parameterize the operation.
apply(experiment)[source]

Assign events to a cluster.

Assigns each event to one of the k-means centroids from estimate(), then groups together events in the same cluster hierarchy.

Parameters: experiment (Experiment) – the Experiment to apply the gate to. A new Experiment with the gate applied to it. TODO - document the extra statistics Experiment
default_view(**kwargs)[source]

Returns a diagnostic plot of the Gaussian mixture model.

Parameters: channels (List(Str)) – Which channels to plot? Must be contain either one or two channels. scale (List({‘linear’, ‘log’, ‘logicle’})) – How to scale the channels before plotting them density (bool) – Should we plot a scatterplot or the estimated density function? an IView, call plot() to see the diagnostic plot. IView
class cytoflow.operations.flowpeaks.FlowPeaks1DView[source]

A one-dimensional diagnostic view for FlowPeaksOp. Plots a histogram of the channel, then overlays the k-means centroids in blue.

facets

A read-only list of the conditions used to facet this view.

Type: List(String)
by

A read-only list of the conditions used to group this view’s data before plotting.

Type: List(String)
channel

The channel this view is viewing. If you created the view using default_view(), this is already set.

Type: String
scale

The way to scale the x axes. If you created the view using default_view(), this may be already set.

Type: {‘linear’, ‘log’, ‘logicle’}
op

The IOperation that this view is associated with. If you created the view using default_view(), this is already set.

Type: Instance(IOperation)
xfacet, yfacet

Set to one of the conditions in the Experiment, and a new row or column of subplots will be added for every unique value of that condition.

Type: String
huefacet

Set to one of the conditions in the in the Experiment, and a new color will be added to the plot for every unique value of that condition.

Type: String
huescale

How should the color scale for huefacet be scaled?

Type: {‘linear’, ‘log’, ‘logicle’}
plot(experiment, **kwargs)[source]

Plot the plots.

Parameters: experiment (Experiment) – The Experiment to plot using this view. title (str) – Set the plot title xlabel, ylabel (str) – Set the X and Y axis labels huelabel (str) – Set the label for the hue facet (in the legend) legend (bool) – Plot a legend for the color or hue facet? Defaults to True. sharex, sharey (bool) – If there are multiple subplots, should they share axes? Defaults to True. row_order, col_order, hue_order (list) – Override the row/column/hue facet value order with the given list. If a value is not given in the ordering, it is not plotted. Defaults to a “natural ordering” of all the values. height (float) – The height of each row in inches. Default = 3.0 aspect (float) – The aspect ratio of each subplot. Default = 1.5 col_wrap (int) – If xfacet is set and yfacet is not set, you can “wrap” the subplots around so that they form a multi-row grid by setting col_wrap to the number of columns you want. sns_style ({“darkgrid”, “whitegrid”, “dark”, “white”, “ticks”}) – Which seaborn style to apply to the plot? Default is whitegrid. sns_context ({“paper”, “notebook”, “talk”, “poster”}) – Which seaborn context to use? Controls the scaling of plot elements such as tick labels and the legend. Default is talk. despine (Bool) – Remove the top and right axes from the plot? Default is True. min_quantile (float (>0.0 and <1.0, default = 0.001)) – Clip data that is less than this quantile. max_quantile (float (>0.0 and <1.0, default = 1.00)) – Clip data that is greater than this quantile. lim ((float, float)) – Set the range of the plot’s data axis. orientation ({‘vertical’, ‘horizontal’}) num_bins (int) – The number of bins to plot in the histogram. Clipped to [100, 1000] histtype ({‘stepfilled’, ‘step’, ‘bar’}) – The type of histogram to draw. stepfilled is the default, which is a line plot with a color filled under the curve. density (bool) – If True, re-scale the histogram to form a probability density function, so the area under the histogram is 1. linewidth (float) – The width of the histogram line (in points) linestyle ([‘-‘ | ‘–’ | ‘-.’ | ‘:’ | “None”]) – The style of the line to plot alpha (float (default = 0.5)) – The alpha blending value, between 0 (transparent) and 1 (opaque). color (matplotlib color) – The color to plot the annotations. Overrides the default color cycle. plot_name (str) – If this IView can make multiple plots, plot_name is the name of the plot to make. Must be one of the values retrieved from enum_plots().
class cytoflow.operations.flowpeaks.FlowPeaks2DView[source]

A two-dimensional diagnostic view for FlowPeaksOp. Plots a scatter-plot of the two channels, then overlays the k-means centroids in blue and the clusters-of-k-means in pink.

facets

A read-only list of the conditions used to facet this view.

Type: List(String)
by

A read-only list of the conditions used to group this view’s data before plotting.

Type: List(String)
xchannel, ychannel

The channels to use for this view’s X and Y axes. If you created the view using default_view(), this is already set.

Type: String
xscale, yscale

The way to scale the x axes. If you created the view using default_view(), this may be already set.

Type: {‘linear’, ‘log’, ‘logicle’}
op

The IOperation that this view is associated with. If you created the view using default_view(), this is already set.

Type: Instance(IOperation)
xlim, ylim

Set the min and max limits of the plots’ x and y axes.

Type: (float, float)
xfacet, yfacet

Set to one of the conditions in the Experiment, and a new row or column of subplots will be added for every unique value of that condition.

Type: String
huefacet

Set to one of the conditions in the in the Experiment, and a new color will be added to the plot for every unique value of that condition.

Type: String
huescale

How should the color scale for huefacet be scaled?

Type: {‘linear’, ‘log’, ‘logicle’}
plot(experiment, **kwargs)[source]

Plot the plots.

Parameters: experiment (Experiment) – The Experiment to plot using this view. title (str) – Set the plot title xlabel, ylabel (str) – Set the X and Y axis labels huelabel (str) – Set the label for the hue facet (in the legend) legend (bool) – Plot a legend for the color or hue facet? Defaults to True. sharex, sharey (bool) – If there are multiple subplots, should they share axes? Defaults to True. row_order, col_order, hue_order (list) – Override the row/column/hue facet value order with the given list. If a value is not given in the ordering, it is not plotted. Defaults to a “natural ordering” of all the values. height (float) – The height of each row in inches. Default = 3.0 aspect (float) – The aspect ratio of each subplot. Default = 1.5 col_wrap (int) – If xfacet is set and yfacet is not set, you can “wrap” the subplots around so that they form a multi-row grid by setting col_wrap to the number of columns you want. sns_style ({“darkgrid”, “whitegrid”, “dark”, “white”, “ticks”}) – Which seaborn style to apply to the plot? Default is whitegrid. sns_context ({“paper”, “notebook”, “talk”, “poster”}) – Which seaborn context to use? Controls the scaling of plot elements such as tick labels and the legend. Default is talk. despine (Bool) – Remove the top and right axes from the plot? Default is True. min_quantile (float (>0.0 and <1.0, default = 0.001)) – Clip data that is less than this quantile. max_quantile (float (>0.0 and <1.0, default = 1.00)) – Clip data that is greater than this quantile. xlim, ylim ((float, float)) – Set the range of the plot’s axis. alpha (float (default = 0.25)) – The alpha blending value, between 0 (transparent) and 1 (opaque). s (int (default = 2)) – The size in points^2. marker (a matplotlib marker style, usually a string) – Specfies the glyph to draw for each point on the scatterplot. See matplotlib.markers for examples. Default: ‘o’ color (matplotlib color) – The color to plot the annotations. Overrides the default color cycle. plot_name (str) – If this IView can make multiple plots, plot_name is the name of the plot to make. Must be one of the values retrieved from enum_plots().
class cytoflow.operations.flowpeaks.FlowPeaks2DDensityView[source]

A two-dimensional diagnostic view for FlowPeaksOp. Plots the estimated density function of the two channels, then overlays the k-means centroids in blue and the clusters-of-k-means in pink.

facets

A read-only list of the conditions used to facet this view.

Type: List(String)
by

A read-only list of the conditions used to group this view’s data before plotting.

Type: List(String)
xchannel, ychannel

The channels to use for this view’s X and Y axes. If you created the view using default_view(), this is already set.

Type: String
xscale, yscale

The way to scale the x axes. If you created the view using default_view(), this may be already set.

Type: {‘linear’, ‘log’, ‘logicle’}
op

The IOperation that this view is associated with. If you created the view using default_view(), this is already set.

Type: Instance(IOperation)
xlim, ylim

Set the min and max limits of the plots’ x and y axes.

Type: (float, float)
xfacet, yfacet

Set to one of the conditions in the Experiment, and a new row or column of subplots will be added for every unique value of that condition.

Type: String
huefacet

Set to one of the conditions in the in the Experiment, and a new color will be added to the plot for every unique value of that condition.

Type: String
huescale

How should the color scale for huefacet be scaled?

Type: {‘linear’, ‘log’, ‘logicle’}
plot(experiment, **kwargs)[source]

Plot the plots.

Parameters: experiment (Experiment) – The Experiment to plot using this view. title (str) – Set the plot title xlabel, ylabel (str) – Set the X and Y axis labels huelabel (str) – Set the label for the hue facet (in the legend) legend (bool) – Plot a legend for the color or hue facet? Defaults to True. sharex, sharey (bool) – If there are multiple subplots, should they share axes? Defaults to True. row_order, col_order, hue_order (list) – Override the row/column/hue facet value order with the given list. If a value is not given in the ordering, it is not plotted. Defaults to a “natural ordering” of all the values. height (float) – The height of each row in inches. Default = 3.0 aspect (float) – The aspect ratio of each subplot. Default = 1.5 col_wrap (int) – If xfacet is set and yfacet is not set, you can “wrap” the subplots around so that they form a multi-row grid by setting col_wrap to the number of columns you want. sns_style ({“darkgrid”, “whitegrid”, “dark”, “white”, “ticks”}) – Which seaborn style to apply to the plot? Default is whitegrid. sns_context ({“paper”, “notebook”, “talk”, “poster”}) – Which seaborn context to use? Controls the scaling of plot elements such as tick labels and the legend. Default is talk. despine (Bool) – Remove the top and right axes from the plot? Default is True. min_quantile (float (>0.0 and <1.0, default = 0.001)) – Clip data that is less than this quantile. max_quantile (float (>0.0 and <1.0, default = 1.00)) – Clip data that is greater than this quantile. color (matplotlib color) – The color to plot the annotations. Overrides the default color cycle. xlim, ylim ((float, float)) – Set the range of the plot’s axis. plot_name (str) – If this IView can make multiple plots, plot_name is the name of the plot to make. Must be one of the values retrieved from enum_plots().