evaluate_event_performance.py

#! /usr/bin/env python
'''
Event level performance evaluation quantified in terms of Asimov significance.
It compares the performance of three old strategies (mHmatch, pThigh, pTjb)
with that of the BDT. The BDT performance is evaluated after excluding events
in which the highest BDT score is < threshold. For many threshold values, the
performance can be computed in paralled. 
Output: 
    plot + pickled dictionary
Run:
    python evaluate_event_performance.py --strategy root_tmva \
    --sample_names SM_bkg_photon_jet SM_hh X275 X300 (...) --intervals 21
'''
import cPickle
import glob
import logging
import os
from itertools import izip
from joblib import Parallel, delayed
import numpy as np
import time
from tabulate import tabulate
from bbyy_jet_classifier import utils
from bbyy_jet_classifier.plotting import plot_asimov

def main(strategy, category, lower_bound, intervals):

    logger = logging.getLogger("event_performance.main")
    # -- test N(=intervals) various threshold values in the range [lower_bound, 1]
    #    where lower_bound = 0 for sklearn, = -1 for tmva
    THRESHOLD = np.linspace(lower_bound, 1, intervals)

    # -- print some info to the user to confirm the settings
    logger.info("Strategy: {}".format(strategy))
    logger.info("Category: {}".format(category))
    logger.info("Threshold values: {}".format(THRESHOLD))

    # -- find samples by looking at those contained in ./output/<category>/pickles/
    base_directory = os.path.join("output", category, "pickles")
    sample_names = os.listdir(base_directory)
    bkg_sample_name = [ x for x in sample_names if "bkg" in x ][0]
    logger.info("Processing data from {} samples...".format(len(sample_names)))
    pickle_paths = sum(
        [glob.glob(
                os.path.join(
                    base_directory,
                    sample_name,
                    "{}_event_performance_dump.pkl".format(strategy)
                )
         ) for sample_name in sample_names], []
        # Q: why adding an empty list?
        # A: sum( list_of_lists, [] ) is a quick way to flatten a list of lists without using libraries.
        )
    logger.info("Found {} datasets to load...".format(len(pickle_paths)))

    # -- read in data from each pickle file & evaluate event-level performance
    perf_dict = {}
    for sample_name, path in zip(sample_names,pickle_paths):
        start_time = time.time()
        logger.info("Reading: {}...".format(path))
        d = cPickle.load(open(path, "rb"))
        perf_dict[sample_name] = eval_performance( # performance evaluation
            d["yhat_test_ev"],
            d["yhat_mHmatch_test_ev"],
            d["yhat_pThigh_test_ev"],
            d["yhat_pTjb_test_ev"],
            d["y_event"],
            d["mjb_event"],
            d["w_test"],
            THRESHOLD=THRESHOLD
        )
        logger.info("Done in {:.2f} seconds".format(time.time()-start_time))

    # TO-DO: it would be nicer if the dictionary was indexed by threshold, instead of containing a 2d list of thresholds and asimovs
    headers = sorted([s for s in sample_names if s != bkg_sample_name])
    if hasattr(THRESHOLD, "__iter__"):
        asimov_dict = {
            _sample_name: {
                strategy: map(np.array, [THRESHOLD, [asimov(s, b) for s, b in zip(perf_dict[_sample_name][strategy], perf_dict[bkg_sample_name][strategy])]])
                for strategy in ["BDT", "mHmatch", "pThigh", "pTjb"]
            }
            for _sample_name in headers#[ x for x in sample_names if x != bkg_sample_name ]
        }

    else:
        asimov_dict = {
            _sample_name: {
                strategy: map(np.array, [[THRESHOLD], [asimov(s, b) for s, b in zip(perf_dict[_sample_name][strategy], perf_dict[bkg_sample_name][strategy])]])
                for strategy in ["BDT", "mHmatch", "pThigh", "pTjb"]
            }
            for _sample_name in headers#[ x for x in sample_names if x != bkg_sample_name ]
        }

    # -- Write dictionary of Asimov significances to disk
    utils.ensure_directory(os.path.join("output", "pickles"))
    with open(os.path.join("output", "pickles", "multi_proc_{}.pkl".format(strategy)), "wb") as f:
        cPickle.dump(asimov_dict, f)

    # -- Plot Z_BDT/Z_old for different threshold values
    plot_asimov.bdt_old_ratio(asimov_dict, strategy, 'mHmatch', lower_bound)
    
    # -- Print Asimov significance for different strategies and different samples in tabular form
    #    Each table corresponds to a different threshold value
    for threshold in THRESHOLD:
        #print '\nAsimov significance for threshold = {}:\n{}'.format(threshold, tabulate(
        logger.info('\nAsimov significance for threshold = {}:\n{}'.format(threshold, tabulate(
            [
                [strategy] + [
                    asimov_dict[_class][strategy][1][np.isclose(asimov_dict[_class][strategy][0], threshold)] 
                    for _class in headers
                ] 
                for strategy in ['BDT', 'mHmatch', 'pTjb', 'pThigh']
            ],
            headers=[''] + headers,
            floatfmt=".5f"
        ))
        )

def asimov(s, b):
    """
    Definition:
    -----------
        Calculates signal to background sensitivity according to the Asimov formula
    Args:
    -----
        s: float, the number of jet pairs properly classified as "correct" that fall in the m_jb window
        b: float, the number of jet pairs mistakenly classified as "correct" that fall in the m_jb window
    Returns:
    --------
        The result of the Asimov formula given s and b
    """
    import math
    return math.sqrt(2 * ((s + b) * math.log(1 + (s / b)) - s))


def eval_performance(yhat_test_ev, yhat_mHmatch_test_ev, yhat_pThigh_test_ev, yhat_pTjb_test_ev, y_event, mjb_event, w_test, THRESHOLD):
    """
    Definition:
    -----------
        Log event-level performance outputs as info
    Args:
    -----
        yhat_test_ev: event level numpy array containing the predictions from the BDT for each jet in the event
        yhat_mHmatch_test_ev: event level numpy array containing the predictions from mHmatch for each jet in the event
        yhat_pThigh_test_ev: event level numpy array containing the predictions from pThigh for each jet in the event
        yhat_pTjb_test_ev: event level numpy array containing the predictions from pTjb for each jet in the event
        y_event: event level numpy array containing the truth labels for each jet in the event
        mjb_event: event level numpy array containing the values of m_jb for each jet in the event
        THRESHOLD: an integer or iterable of integers
    """
    logger = logging.getLogger("eval_performance")
    logger.info("BDT:     Number of correctly classified events = {:5} out of {} events having a correct pair".format(*count_correct_total(yhat_test_ev, y_event)))
    logger.info("mHmatch: Number of correctly classified events = {:5} out of {} events having a correct pair".format(*count_correct_total(yhat_mHmatch_test_ev, y_event)))
    logger.info("pThigh:  Number of correctly classified events = {:5} out of {} events having a correct pair".format(*count_correct_total(yhat_pThigh_test_ev, y_event)))
    logger.info("pTjb:    Number of correctly classified events = {:5} out of {} events having a correct pair".format(*count_correct_total(yhat_pTjb_test_ev, y_event)))
    logger.info("Number of events without any correct pair = {}".format(sum([sum(y_event[ev]) == 0 for ev in xrange(len(y_event))])))

    # check whether selected pair has m_jb in mass window for truly correct and truly incorrect pairs
    # -- this will make little sense for SM_merged because lots of events are bkg and shouldn"t fall in m_bj window, but can"t tell them
    # -- apart without mcChannel number --> use unmerged samples in that case
    # 3 categories: truly correct pair present and got it right, truly correct pair present and got it wrong, no correct pair present
    # -- check this for all 3 strategies (BDT, mHmatch, pThigh)
    # 1. was there a correct pair?
    correct_present_truth = np.array([sum(ev) == 1 for ev in y_event])
    # ^ this is strategy agnostic, can be calculated outside
    in_BDT = in_mjb_window(mjb_event, y_event, yhat_test_ev, w_test, correct_present_truth, "BDT", THRESHOLD)
    in_mHmatch = in_mjb_window(mjb_event, y_event, yhat_mHmatch_test_ev, w_test, correct_present_truth, "mHmatch", THRESHOLD)
    in_pThigh = in_mjb_window(mjb_event, y_event, yhat_pThigh_test_ev, w_test, correct_present_truth, "pThigh", THRESHOLD)
    in_pTjb = in_mjb_window(mjb_event, y_event, yhat_pTjb_test_ev, w_test, correct_present_truth, "pTjb", THRESHOLD)
    return {"BDT": in_BDT, "mHmatch": in_mHmatch, "pThigh": in_pThigh, "pTjb" : in_pTjb}


def count_correct_total(yhat, y):
    """
    Definition:
    -----------
        Quantify the number of events in which the correct jet pair was assigned the highest classifier score
    Args:
    -----
        yhat: event level numpy array containing the predictions for each jet in the event
        y:    event level numpy array containing the truth labels for each jet in the event
    Returns:
    --------
        n_correct_classifier: int, number of events in which the correct jet pair was assigned the highest classifier score
        n_correct_truth:      int, total number of events with a "correct" jet pair
    """
    # -- find how many times we find the correct pair in all events that do have a correct pair
    # correct_classifier = a truly correct pair existed (sum(y[ev]) == 1) and we got it right (np.argmax(yhat[ev]) == np.argmax(y[ev]))
    n_correct_classifier = sum([np.argmax(yhat[ev]) == np.argmax(y[ev]) for ev in xrange(len(y)) if sum(y[ev]) == 1])
    # correct_truth = a truly correct pair exists
    n_correct_truth = sum([sum(y[ev]) == 1 for ev in xrange(len(y))])
    return n_correct_classifier, n_correct_truth


def _weightedsum_eventsinmjb(weights_in_mjb, yhat, slicer, thresh):
    sliced_weights = weights_in_mjb[slicer]
    sliced_yhat = np.array(yhat)[slicer]
    return np.sum(w[np.argmax(y)] for w, y in izip(sliced_weights, sliced_yhat) if max(y) >= thresh)


def in_mjb_window(mjb_event, y_event, yhat_test_ev, w_test, correct_present_truth, strategy, THRESHOLD):
    logger = logging.getLogger("mjb_window - " + strategy)
    # -- if there was a correct pair and we got it right, how many times does it fall into m_jb? how many times does it not?
    # -- if there was a correct pair and we got it wrong, how many times does it fall into m_jb? how many times does it not?
    # -- if there was no correct pair, how many times does the pair we picked fall into m_jb? how many times does it not?
    # 1. was there a correct pair?
    # correct_present_truth
    # 2. does the bdt agree with the truth label? aka got it right?
    agree_with_truth = np.array([(np.argmax(yhat) == np.argmax(y)) for yhat, y in izip(yhat_test_ev, y_event)])
    # 3. truly correct present and selected (A)
    correct_truth_correct_BDT = np.array(np.logical_and(correct_present_truth, agree_with_truth))
    # 4. truly correct present but selected other pair (B)
    correct_truth_incorrect_BDT = np.array(np.logical_and(correct_present_truth, -agree_with_truth))
    # 5. no correct jet present = - correct_present_truth (C)

    # -- look at mjb for these 3 cases:
    # -- boolean
    in_mjb = [np.logical_and(mjb_event[ev] < 135, mjb_event[ev] > 95) for ev in xrange(len(mjb_event))]

    # -- weights * boolean
    weights_in_mjb = np.array([_w * _m for _w, _m in izip(w_test, in_mjb)])

    if hasattr(THRESHOLD, "__iter__"):

        # num_inX are lists in this scenario
        num_inA = Parallel(n_jobs=20, verbose=True)(delayed(_weightedsum_eventsinmjb)(weights_in_mjb, yhat_test_ev, correct_truth_correct_BDT, thresh) for thresh in THRESHOLD)
        num_inB = Parallel(n_jobs=20, verbose=True)(delayed(_weightedsum_eventsinmjb)(weights_in_mjb, yhat_test_ev, correct_truth_incorrect_BDT, thresh) for thresh in THRESHOLD)
        num_inC = Parallel(n_jobs=20, verbose=True)(delayed(_weightedsum_eventsinmjb)(weights_in_mjb, yhat_test_ev, -correct_present_truth, thresh) for thresh in THRESHOLD)

        return np.array([num_inA, num_inB, num_inC]).sum(axis=0)

    else:
        num_inA = _weightedsum_eventsinmjb(weights_in_mjb, yhat_test_ev, correct_truth_correct_BDT, thresh=THRESHOLD)
        num_inB = _weightedsum_eventsinmjb(weights_in_mjb, yhat_test_ev, correct_truth_incorrect_BDT, thresh=THRESHOLD)
        num_inC = _weightedsum_eventsinmjb(weights_in_mjb, yhat_test_ev, -correct_present_truth, thresh=THRESHOLD)

        logger.info("Total number of events with a correct pair present and identified = {}".format(sum((w * c) for w, c in izip(w_test, correct_truth_correct_BDT))))
        logger.info("Of these events, {} fall in m_jb window".format(num_inA))
        logger.info("Total number of events with a correct pair present but a different one selected = {}".format(sum((w * c) for w, c in izip(w_test, correct_truth_incorrect_BDT))))
        logger.info("Of these events, {} fall in m_jb window".format(num_inB))
        logger.info("Total number of events without a correct pair = {}".format(sum((w * c) for w, c in izip(w_test, -correct_present_truth))))
        logger.info("Of these events, out of the ones selected by the classifier, {} fall in m_jb window".format(num_inC))
        logger.info("Total number of events in the m_jb window = {}".format(num_inA + num_inB + num_inC))
        return [num_inA + num_inB + num_inC]


if __name__ == "__main__":
    import sys
    import argparse
    utils.configure_logging()

    parser = argparse.ArgumentParser(description="Check event level performance")
    #parser.add_argument("--sample_names", help="list of names of samples to evaluate", type=str, nargs="+", default=[])
    parser.add_argument("--strategy", type=str, default="skl_BDT",
        help="Strategy to evaluate. Options are: root_tmva, skl_BDT. Default: skl_BDT")
    parser.add_argument("--category", type=str, default="low_mass",
        help="Trained classifier to use for event-level evaluation. Examples are: low_mass, high_mass. Default: low_mass")
    parser.add_argument("--intervals", type=int, default=21,
        help="Number of threshold values to test. Default: 21")
    args = parser.parse_args()
    if args.strategy == 'skl_BDT':
        lower_bound = 0
    elif args.strategy == 'root_tmva':
        lower_bound = -1
    else:
        raise ValueError("Unknown strategy. The only options are root_tmva and skl_BDT.")
    sys.exit(main(args.strategy, args.category, lower_bound, args.intervals))