percdata

Computes percentiles (quantiles) for selected numeric columns. By default, six bottom percentiles (0th to 0.5th) and six top percentiles (99.5th to 100th) are calculated. The function supports grouping.

Fast, efficient, and versatile preprocessing and reshaping of tabular
and time-series data. Most heavy routines are implemented in 'C++' via
'Rcpp', with optional 'OpenMP' parallelization and 'SIMD' acceleration
('AVX2' / 'AVX-512') on supported hardware. The 0.1.8 release rewrites
the cleaning routines in 'C++' and delivers a 1.1–1146× speedup over
0.1.5. The 'melt()' and 'dcast()' reshaping functions achieve a
0.6×–1628.9× speedup for 'melt()' and a 1.9×–799.8× speedup for
'dcast()' relative to every one of the seven major alternatives in
the R and Python ecosystems, at every tested scale (from 1,000 to
100,000,000 rows), and produce output identical to 'reshape2',
'data.table', 'tidyr', 'pandas', 'polars', 'dask', and 'duckdb'.
Core preprocessing steps include variable deletion by missing
fraction, observation deletion by consecutive missing runs,
point-by-point weighted outlier removal via conditional extremum,
traditional percentile-based outlier removal, and linear
interpolation within short time periods. The package also provides
fast reshaping, descriptive statistics, missing-value diagnosis,
multiple imputation strategies, winsorization, several outlier
detection methods (IQR, MAD, percentile), data transformation and
standardization, categorical encoding, duplicate removal, data
validation, data quality reporting, and stratified sampling.
Feature-engineering helpers cover binning, high-correlation and
low-variance filtering, and string cleaning. Time-series tools
cover detrending, diurnal-cycle removal, rolling statistics, lag
creation, resampling, simple decomposition, day/night and season
flags, log returns, drift detection, and panel balancing.
Fit/transform-style machine-learning interfaces prevent data
leakage during preprocessing. Methods are based on, and improved
from: Liang, C.-S., Wu, H., Li, H.-Y., Zhang, Q., Li, Z. & He,
K.-B. (2020) <doi:10.1016/j.scitotenv.2020.140923>. This work
was supported by the National Natural Science Foundation of China
(No. 12301674).

Chun-Sheng Liang

dataprep

Fast, Efficient, and Versatile Data Preprocessing and Reshaping
with 'C++', 'OpenMP' & 'SIMD'

Hao Wu

Hai-Yan Li

Qiang Zhang

Zhanqing Li

Ke-Bin He

percdata function

<dl> <dt>data</dt>
<dd>A data frame, matrix, or numeric vector. If a vector, a data frame is created internally.</dd> <dt>cols</dt>
<dd>Column indices or names of numeric variables. If <code>NULL</code>, all numeric columns are used.</dd> <dt>group</dt>
<dd>Optional grouping column index or name. If provided, percentiles are computed separately for each group.</dd> <dt>diff</dt>
<dd>Common difference between quantile probabilities. Default is 0.1.</dd> <dt>part</dt>
<dd>Which parts to return: <code>"both"</code> (default), <code>"bottom"</code>, or <code>"top"</code>. For backward compatibility, <code>part</code> also accepts the integer codes <code>2</code> (<code>"both"</code>), <code>0</code> (<code>"bottom"</code>), and <code>1</code> (<code>"top"</code>).</dd> <dt>na.rm</dt>
<dd>Logical; if <code>TRUE</code>, NA values are removed before quantile computation.</dd> <dt>verbose</dt>
<dd>Logical; if <code>TRUE</code>, prints timing message.</dd></dl>

Arguments

Chun-Sheng Liang &lt;chun-shengliang@qq.com&gt;

Author

Calculate top and bottom percentiles of selected variables — percdata

<dl>

 <dt>data</dt>
<dd>A data frame, matrix, or numeric vector. If a vector, a data frame is created internally.</dd>

 <dt>cols</dt>
<dd>Column indices or names of numeric variables. If <code>NULL</code>, all numeric columns are used.</dd>

 <dt>group</dt>
<dd>Optional grouping column index or name. If provided, percentiles are computed separately for each group.</dd>

 <dt>diff</dt>
<dd>Common difference between quantile probabilities. Default is 0.1.</dd>

 <dt>part</dt>
<dd>Which parts to return: <code>"both"</code> (default), <code>"bottom"</code>, or <code>"top"</code>. For backward compatibility, <code>part</code> also accepts the integer codes <code>2</code> (<code>"both"</code>), <code>0</code> (<code>"bottom"</code>), and <code>1</code> (<code>"top"</code>).</dd>

 <dt>na.rm</dt>
<dd>Logical; if <code>TRUE</code>, NA values are removed before quantile computation.</dd>

 <dt>verbose</dt>
<dd>Logical; if <code>TRUE</code>, prints timing message.</dd>

</dl>

percdata: Calculate top and bottom percentiles of selected variables

Description

Usage

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Arguments

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Examples