1954 search results for "time series"

Butterworth filter overshoot

January 15, 2014
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Butterworth filter overshoot

Introduction Butterworth filters with order other than 1 have an overshoot phenomenon that can be problematic in some cases. For example, if smoothing is used on an estimate of kinetic energy, overshoots might yield negative values that are nonphysical. This post simply illustrates this with made-up data that the reader can experiment with. Methods First, create and plot...

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Smoothing CTD profiles

January 11, 2014
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Smoothing CTD profiles

Introduction Smoothing hydrographic profiles with conventional time-series methods is problematic for two reasons: (a) the data are commonly not equi-spaced in depth and (b) the data seldom lack trends in depth. The issues and their solutions are illustrated without much discussion here. The first step in making the graph shown above is to load the oce library and...

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Summarising multivariate palaeoenvironmental data

January 9, 2014
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Summarising multivariate palaeoenvironmental data

The horseshoe effect is a well known and discussed issue with principal component analysis (PCA) (e.g. Goodall 1954; Swan 1970; Noy-Meir & Austin 1970). Similar geometric artefacts also affect correspondence analysis (CA). In part 1 of this series I looked at the implications of these “artefacts” for the recovery of temporal or single dominant gradients from multivariate palaeoecological data....

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Fast-track publishing using knitr: exporting images for sharing and press (part III)

January 7, 2014
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Fast-track publishing using knitr: exporting images for sharing and press (part III)

(This article was first published on G-Forge » R, and kindly contributed to R-bloggers) Images can be a powerful medium if used right. The image is CC by alemdag. Fast-track publishing using knitr is a short series on how I use knitr to speedup publishing in my research. This is the third article in the series devoted to plots....

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analyze the national immunization survey (nis) with r

January 6, 2014
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for twenty years now, the centers for disease control and prevention (cdc) has been random-digit-dialing american households to ask parents which vaccinations their little tykes have received.  and since vaccination history might not be at the for...

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Cran2deb4ubuntu: An Update for 2014

January 5, 2014
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I have been a little quiet on the update front for the past few months, so I thought I would give a quick update as 2014 begins. Between increased responsibilities at work (pseudo-department chair) and some family health issues, work on cran2deb4ubunt...

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Fast-track publishing using knitr: intro (part I)

December 30, 2013
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Fast-track publishing using knitr: intro (part I)

Fast-track publishing using knitr is a short series on how I use knitr to get my articles faster published. By fast-track publishing I mean eliminating as many of the obstacles as possible during the manuscript phase, and not the fast-track some journals offer. In this first introductory article I will try to (1) define the main groups of...

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The performance gains from switching R’s linear algebra libraries

The performance gains from switching R’s linear algebra libraries

What is often forgotten in the so-called data analysis "language wars” is that, across most of these languages, many common computations are performed using outsourced dynamically linked math libraries. For example, R; Python's Numpy; Julia; Matlab; and Mathematica all make heavy use of the BLAS linear algebra API. As a result, R can't be properly »more

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How fair is White Elephant?

December 24, 2013
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How fair is White Elephant?

This article was first published on analyze stuff. It has been contributed to Anything but R-bitrary in celebration of its introductory post.By Max Ghenis Welcome to analyze stuff! For our first post, I wanted to reflect on the time of year; after all, ‘tis the season for hams and yams, caroling and sledding, and of...

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How fair is White Elephant?

December 24, 2013
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How fair is White Elephant?

Welcome to analyze stuff! For our first post, I wanted to reflect on the time of year; after all, ‘tis the season for hams and yams, caroling and sledding, and of course gifts! One popular party gift exchange game is the White Elephant, where each person brings a wrapped (typically regifted or otherwise odd-ball)...

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