Cytolysis

A python module to facilitate the automatic analysis cytosim simulations. By itself, it does not include many analysis functions but mostly an API.

Installation

pip3 install cytolysis

Requirements

Requires Python3 and modules numpy, pandas.
To visualize the simulation in iPython (Jupyter Notebook), you should install ipyvolume :

conda install -c conda-forge ipyvolume

Practical examples

We provide several examples where we analyze the result of a simulation for an example config file. This simulation has two asters of microtubules brought to the center by the rigidity of the microtubules and by the activity of dyneins.

An example counting the number of fiber points for each filament, and at each time:

python3 examples/example_fibers.py

An example where we compute the fiber bending energy as a function of time

python3 examples/example_fiber_curvature.py

We can also analyze any cytosim class that can be reported, by creating custom objects. For example, this is done here for solids and spaces :

python3 examples/example_solid.py

Several ipython notebooks are also available in the notebook folder.

Interface (examples)

Import the module :

from cytolysis import cytosim_analysis as ana

The main class is Simulation, a list of time frames. Create an instance of a simulation analysis via :

microtubule_reports={'points' : 'fiber_points.txt' }
simul = ana.Simulation(reports={'microtubule': microtubule_reports},
                        config='config.cym') 

You can specify analysis functions for the different simulation objects, specifying by object name :

def count_points(fiber):
    return fiber.shape[0]

def count_fibers(frame):
    return len(frame.fibers)

analyzer={}
analyzer['microtubule'] = {'pts_number': count_points}
analyzer['frame'] = {'fib_number': count_fibers}

You can then run the analysis :

simul.make_analysis(analyzer=analyzer)

The analysis of objects is stored as pandas dataframes in the frames. For exemple, the analysis of microtubules for frame 5 is stored in :

simul[5].analysis['microtubule']

Similarly, the analysis for couples 'arp_2_3' at frame 10 is stored in :

simul[10].analysis['arp_2_3']

Simul is a set of frames, and the results of the analysis of all frames can be accessed in :

simul.frames_analysis

While a global analysis of the simulation is available in :

simul.analysis

The module contains a function to export analysis dataframes into csv files :

ana.export_analysis(simul.frames_analysis, 'frames.csv')

There is also experimental support for showing the system in 3D in notebooks :

simul.show(frame_number)

Components

Simulation

The class Simulation is a set of frames, instances of the class Frame. Input arguments :

• reports : a dictionary of dictionaries of pathes to report files.
• options : a dictionary of dictionaries of options.
• config : path to the config file
• dim : dimensionality of the simulation (by default, 3)

Simulation has a method make_analysis to perform the analysis. This takes as option analyzer, a dictionary of dictionaries of analysis functions.

simulation.make_analysis performs the analysis specified in analyzer["simulation"], and the result is stored in simulation.analysis.

As a set of frames , simulation implements simulation.analyze(frame, analyzer=..., ... ) (see Object_set). This performs the analysis specified in analyzer['frame']. The results are stored in simulation.frames_analysis

Frame

Each frame contains several types of dictionaries of object_sets. Each dictionary is of the type : { name : object_set }. For instance, if fibers have been loaded, they are available in frame.objects["fibers"].

Once the analysis has been performed, the analysis results are stored in :

• frame.analysis[object_type], e.g. frame.analysis["fibers"].

Frame implements the analysis method frame.make_analysis(...) that calls the object_set.analyze(object, ...) method of all object sets.

Object_set

Object set is a class derived from list. Fibers_set and Couples_set are derived from Object_set. Input arguments :

• name : name of the object (e.g. "microtubule")
• type : type of the object (e.g. "fiber")
  Optional input arguments :
• config : the pile read from the configuration file
• build : a function to build the object set from the reports

Beyond the initialization (init) method, object set need to implement the methods :

• object_set.analyze(object, ... ) : a function that analyzes object, a given item from the object set
• object_set.type : object type
• object_set.name : object name
• object_set.id : object id (a number)
• object_set.properties : a dictionary of properties read from the config file
• object_set.show : a way to plot the object set in 3D using iPyVolume

Analysis

All the analysis results (simulation.analysis, frame.analysis["fibers"], etc.) are stored as Pandas dataframes and, by default, exported as csv files. Examples:

• frame.analysis["fiber"][fiber_name] is a dataframe with as many rows as there are fibers.
• simulation.frame_analysis is a dataframe with as many rows as there are frames.
• simulation.analysis is a dataframe with a single row.

Therefore, if one wants to look at the distribution of some property among objects for a given frame, one would export frame.analysis[object_type][object_name].
If one wants to analyze something over time, one would export simulation.frame_analysis.
If one wants a single line to sumarize the simulation, for instance in order to compare different simulations, one would export simulation.analysis.

Plotting

When used in iPython, cytolysis can represent the system in 3D, and allows to plot objects differently according to their properties, see this example.