# 2353 search results for "time series"

## Finding patterns in time series using regular expressions

May 17, 2013
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Regular expressions are a fantastic tool when you’re looking for patterns in time series. I wish I’d realised that sooner. Here’s a timely example: traditionally, when you have two successive quarters of negative GDP growth, you’re in recession. We have a quarterly GDP time series for Australia, and we want to know how many recessions

## Time series data in R

April 22, 2013
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Handling time series data in R In this blog post I want to write some thoughts about handling time series data in R. In contrast to cross-sectional data, in time series applications each observation has an additional component besides it’s value: the point of time. This requires some additional efforts, for example: x-axis has to

## A nifty line plot to visualize multivariate time series

April 1, 2013
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A few days ago a colleague came to me for advice on the interpretation of some data. The dataset was large and included measurements for twenty-six species at several site-year-plot combinations. A substantial amount of effort had clearly been made to ensure every species at every site over several years was documented. I don’t pretend

## Quandl: A Wikipedia for Time Series Data

February 20, 2013
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This guest post is by Tammer Kamel, Founder of Quandl Finding and formatting numerical data for analysis in R or Excel or indeed any application is a pain that all real world data analysts know all too well. In aggregate I have probably spent weeks of my life trying to find data on the web. And several more weeks...

## Time series cross-validation 5

January 24, 2013
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The caret package for R now supports time series cross-validation!  (Look for version 5.15-052 in the news file).  You can use the createTimeSlices function to do time-series cross-validation with a fixed window, as well as a growin...

## Lomb-Scargle periodogram for unevenly sampled time series

January 10, 2013
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In the natural sciences, it is common to have incomplete or unevenly sampled time series for a given variable. Determining cycles in such series is not directly possible with methods such as Fast Fourier Transform (FFT) and may require some degree o...

## Lomb-Scargle periodogram for unevenly sampled time series

January 10, 2013
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In the natural sciences, it is common to have incomplete or unevenly sampled time series for a given variable. Determining cycles in such series is not directly possible with methods such as Fast Fourier Transform (FFT) and may require some degree of interpolation to fill in gaps. An alternative is the Lomb-Scargle method (or...

## Generating polygon boundaries for plotting simple time series data with missing data

December 19, 2012
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Every so often I want to plot some data with pretty upper and lower error bounds, such as temperature data through time, perhaps with the maximum and minimum temperature range or standard error bounds for averaged data. The polygon( ) function can make those sorts of pretty plots. However, I’ll often have chunks of missing

## Extending Commodity time series

November 21, 2012
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I want to follow up with Extending Gold time series post by showing how we can extend Commodity time series. Most Commodity ETFs began trading in 2006, please see the List of Commodity ETFs page. I will use DBC – PowerShares DB Commodity Fund, one on the most liquid Commodity ETFs as my proxy for

## Extending Gold time series

September 10, 2012
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While back-testing trading strategies I want all assets to have long history. Unfortunately, sometimes there is no tradeable stock or ETF with sufficient history. For example, I might use GLD as a proxy for Gold allocation, but GLD is only began trading in November of 2004. We can extend the GLD’s historical returns with its