813 search results for "SQL"

Parallelism via “parSapply”

December 13, 2014
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In an earlier post, I used mclapply to kick off parallel R processes and to demonstrate inter-process synchronization via the flock package. Although I have been using this approach to parallelism for a few years now, I admit, it has certain important disadvantages. It works only on a single machine, and also, it doesn’t work

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O’Reilly Data Scientist Salary and Tools Survey, November 2014

December 10, 2014
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O’Reilly Data Scientist Salary and Tools Survey, November 2014

The O'Reilly Data Scientist Survey for 2014 is out, with fresh data on the salaries and tools used by data scientists. Jon King has a summary of the results, but not much has changed since last year: median income is down very slightly ($100k in 2013 vs $98k in 2014), and the most popular analysis tools (excluding operating systems)...

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Identifying Position Change Groupings in Rank Ordered Lists

December 9, 2014
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Identifying Position Change Groupings in Rank Ordered Lists

The title says it all, doesn’t it?! Take the following example – it happens to show race positions by driver for each lap of a particular F1 grand prix, but it could be the evolution over time of any rank-based population. The question I had in mind was – how can I identify positions that

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dplyr – some more reflections

December 4, 2014
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Yesterday, I published a post here on DataScience.LA with a simple/basic benchmark for dplyr. It...

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The World We Live In #3: Breastfeeding

December 1, 2014
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The World We Live In #3: Breastfeeding

Facts are stubborn, but statistics are more pliable (Mark Twain) According to World Health Organization, exclusive breastfeeding is recommended up to 6 months of age, with continued breastfeeding along with appropriate complementary foods up to two years of age or beyond. Thus, the defining characteristic of continued breastfeeding is that the infant between 6 months and … Continue reading...

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Storing Forecasts in a Database

November 29, 2014
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In my last post I mentioned that I started using RSQLite to store computed results. No rocket science here, but my feeling is that this might be useful to others, hence, this post. This can be done using any database, but I will use (R)SQLite as an illustration. Let’s assume we are running a long

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R, an Integrated Statistical Programming Environment and GIS

November 27, 2014
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R, an Integrated Statistical Programming Environment and GIS

This article was originally published in Geoinformatics magazine. R is well known as a powerful, extensible and relatively fast statistical programming language and open software project with a command line interface (CLI). What is less well known is that R also has cutting edge spatial packages that allow it to behave as a fully featured Geographical Information System...

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Synchronization for R with the flock Package

November 20, 2014
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Have you tried synchronizing R processes? I did and it wasn’t straightforward. In fact, I ended up creating a new package – flock. One of the improvements I did not too long ago to my R back-testing infrastructure was to start using a database to store the results. This way I can compute all interesting

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The ensurer package (validation inside pipes)

November 19, 2014
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The ensurer package (validation inside pipes)

Guest post by Stefan Holst Milton Bache on the ensurer package. If you use R in a production environment, you have most likely experienced that some circumstances change in ways that will make your R scripts run into trouble. Many things can go wrong; package updates, external data sources, daylight savings time, etc. There is a general

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analyze the national incident-based reporting system (nibrs) with r and monetdb

November 11, 2014
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in 2012, more than one quarter of the united states population lived in the jurisdiction of a police department that submitted details about every crime to a central repository maintained by the fbi.  a production of the uniform crime reports (ucr) program, the national incident-based reporting system (nibrs) compiles statistics from police agencies in thirty five states...

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