SimuChemPC: SimuChemPC

In SimuChemPC: Simulation process of 4 selection methods in predicting chemical potent compounds

Description

This function executes a simulation to compare 4 methods for predicting potent compounds. These methods are EI, GP, NN and RA.

Usage

SimuChemPC(dataX, dataY, method="RA", experiment=1)

Arguments

dataX	m * n martrix of data (features/descriptors).
dataY	m * 1 matrix of target values consist of potencies, pIC50 or other measurements of compound affinities that are desired to be maximized.
method	One of "EI", "GP", "NN" or "RA".
experiment	An integer value that indicates a number by which experiment repeats. In our published experiment it was set to 25.

Details

This function withholds 4 simulation methods to predict potent compounds . method can be RA, NN , EI or GP. The explanation of the abbreviations is listed below.

RA selection: One compound will be selected randomly and added to train data each time.

NN selection: The compound which is nearest (based on Tonimito Coefficient) to the most potent compound in training data is selected and added to train data.

EI selection A compound for which maximum expected potency improvement is reached, is selected and then it is added to train data.

GP selection A compound holding maximum potency in test data is selected.

Feature selection Feature selection employed in this package is based on Spearman Rank Correlation such that before each training step those attributes in which revealed a significant Spearman rank correlation with the logarithmic potency values (q-value < 5 are computed from original p-values via the multiple testing correction method by Benjamini and Hochberg.

The purpose of simulation step Simulation step is employed to select the compound(in the case where input files are chemical compounds) in which maximal expected potency improvement is met. Subsequently, this compound is added to train data and simulation continues until all test data are consumed. Finally, the number of simulation steps is determined which the algorithm used to select the most potent compound in the "original" test set.

In this code, given our data sets (chemical compounds), we do the followings:

1. We split our data into two distinguish parts namely Train and Test data

2. We do normalization on both parts

3. We employ a specific feature selection algorithm (i.e. Multiple Testing Correction) to overcome high dimensionality

4. Then we benefit Gaussian Process Regression in order to learn our model iteratively such that in each iteration training data are trained, the model is learnt and prediction is done for test data. One compound holding specific property will be added to train data and the progress will repeat until no test data is left.

Result of this work is accepted in the Journal of Chemical Information and Modeling within the subject "Predicting Potent Compounds via Model-Based Global Optimization".

Value

returns a matrix (m * experiment) of original potencies in test set.

Author(s)

Mohsen Ahmadi

References

1.Predicting Potent Compounds via Model-Based Global Optimization, Journal of Chemical Information and Modeling, 2013, 53 (3), pp 553-559, M Ahmadi, M Vogt, P Iyer, J Bajorath, H Froehlich. 2.Software MOE is used to calculate the numerical descriptors in data sets. Ref: http://www.chemcomp.com/MOE-Molecular_Operating_Environment.htm 3.ChEMBL was the source of the compound data and potency annotations in data sets. Ref: https://www.ebi.ac.uk/chembl/

Examples

x = as.data.frame(array(1:100, dim=c(20,5)))
y = as.matrix(as.numeric(array(1:20, dim=c(20,1))))
SimuChemPC(x, y, "RA", 5)

SimuChemPC documentation built on May 2, 2019, 3:30 p.m.