162 research outputs found
Alchemical and structural distribution based representation for improved QML
We introduce a representation of any atom in any chemical environment for the
generation of efficient quantum machine learning (QML) models of common
electronic ground-state properties. The representation is based on scaled
distribution functions explicitly accounting for elemental and structural
degrees of freedom. Resulting QML models afford very favorable learning curves
for properties of out-of-sample systems including organic molecules,
non-covalently bonded protein side-chains, (HO)-clusters, as well as
diverse crystals. The elemental components help to lower the learning curves,
and, through interpolation across the periodic table, even enable "alchemical
extrapolation" to covalent bonding between elements not part of training, as
evinced for single, double, and triple bonds among main-group elements
ProcData: An R Package for Process Data Analysis
Process data refer to data recorded in the log files of computer-based items.
These data, represented as timestamped action sequences, keep track of
respondents' response processes of solving the items. Process data analysis
aims at enhancing educational assessment accuracy and serving other assessment
purposes by utilizing the rich information contained in response processes. The
R package ProcData presented in this article is designed to provide tools for
processing, describing, and analyzing process data. We define an S3 class
"proc" for organizing process data and extend generic methods summary and print
for class "proc". Two feature extraction methods for process data are
implemented in the package for compressing information in the irregular
response processes into regular numeric vectors. ProcData also provides
functions for fitting and making predictions from a neural-network-based
sequence model. These functions call relevant functions in package keras for
constructing and training neural networks. In addition, several response
process generators and a real dataset of response processes of the climate
control item in the 2012 Programme for International Student Assessment are
included in the package
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