An Eager Avocado

Eager Avocado

I give myself very good advice, but I very seldom follow it.

Allocation cost

17 September 2017

Many high-level programming languages allow their users to afford the luxury of extending an existing matrix or vector. The question is, how luxury it can be?

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data.table subsetting

02 March 2017

The data.table package supports a powerful syntax to select rows and columns.

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Non-trivial operation on data.table columns

01 March 2017

This note explores the use of data.table package to calculate pairwise correlation between columns, with iris data set as example.

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Expectation of trials until success

11 September 2016

Example 1 - Fair coin

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[Peer review] A comprehensive evaluation of normalization methods for Illumina high-throughput RNA sequencing data analysis

28 August 2016

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Maximum likelihood fitting a discrete variable distribution

07 July 2016

The package MASS provides a function, fitdistr to fit an observation over discrete distribution using Maximum likelihood.

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String manipulation efficiency

07 July 2016

String concatenation can be done with paste, paste0, sprintf, or .Internal(sprintf).

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How much harm can nested if's do?

07 July 2016

The definition of a(), b(), and sw() below achieve the same effect with different implementations: if else, nested if, and switch

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.Internal(sample)

07 July 2016

.Internal(sample()) requires explicitly 4 arguments in order: n, size, replacement, probabilities

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SAMSeq Demo

30 June 2016

Two-class

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Fast Pearson Correlation

27 June 2016

This note compares the performance of 2 methods for calculating Pearson correlation: R stats::cor function WGCNA::cor function (or corFast)

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Plotting large matrix in R

09 April 2016

a = matrix(rnorm(10000^2),ncol=10000) Ns = c(1000, 5000,10000) times = data.frame(list(N=Ns)) t1 = sapply(Ns, function(n) {system.time(image(a[1:n,1:n],useRaster=T))['elapsed']})

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kNN estimator in action

24 March 2016

-nearest neighbor Entropy estimator

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Read/Write data with rhdf5

18 March 2016

The inconsistency

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Kernel density estimator

10 March 2016

See Lecture by [@gutierrez_kernel].

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Variable transformation

23 February 2016

This article explores three types of transformations

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Recursive indexing failed

18 February 2016

An example where recursive indexing failed error is not clear

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Digit count

22 January 2016

Recursive function

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apply() function

22 January 2016

Data This is the value of matrix a

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