534 search results for "SQL"

Software engineer’s guide to getting started with data science

December 30, 2012
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Software engineer’s guide to getting started with data science

Many of my software engineer friends ask me about learning data science. There are many articles on this subject from renowned data scientists (Dataspora, Gigaom, Quora, Hilary Mason). This post captures my journey (a software engin...

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Opening Large CSV Files in R

December 26, 2012
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Opening Large CSV Files in R

Before heading home for the holidays, I had a large data set (1.6 GB with over 1.25 million rows) with columns of text and integers ripped out of the company (Kwelia) Database and put into a .csv file since I was going to be offline a lot over the break. I tried opening the csv file

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Aggregation by Group in R

December 23, 2012
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Aggregation by Group in R

Efficiency Comparison among 4 Methods above

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Data Import Efficiency – A Case in R

December 23, 2012
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Data Import Efficiency – A Case in R

Below is a piece of R snippet comparing the data import efficiencies among CSV, SQLITE, and HDF5. Similar to the case in Python posted yesterday, HDF5 shows the highest efficiency.

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Chocolate and nobel prize – a true story?

December 22, 2012
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Chocolate and nobel prize – a true story?

Few of us can resist chocolate, but the real question is: should we even try to resist it? The image is CC by Tasumi1968.As a dark chocolate addict I was relieved to see Messerli's ecological study on chocolate consumption and the...

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Removing Records by Duplicate Values in R – An Efficiency Comparison

December 20, 2012
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Removing Records by Duplicate Values in R – An Efficiency Comparison

After posting “Removing Records by Duplicate Values” yesterday, I had an interesting communication thread with my friend Jeffrey Allard tonight regarding how to code this in R, a combination of order() and duplicated() or sqldf(). Afterward, I did a simple efficiency comparison between two methods as below. The comparison result is pretty self-explanatory. In terms

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Querying, parsimony and golden hammers

December 20, 2012
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Querying, parsimony and golden hammers

I love it when things are easy. I love it so much that I’ll spend a great deal of time and effort to keep things simple. At the same time, though, I think there’s some value in expending effort in pursuit of something. If you want to understand a thing, you have to spend time

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analyze the behavioral risk factor surveillance system (brfss) with r and monetdb

December 17, 2012
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experimental.  the behavioral risk factor surveillance system (brfss) aggregates behavioral health data from 400,000 adults via telephone every year.  it's um *clears throat* the largest telephone survey in the world and it's gotta lotta uses...

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Data Science, Data Analysis, R and Python

The October 2012 issue of Harvard Business Review prominently features the words “Getting Control of Big Data” on the cover, and the magazine includes these three related articles:“Big Data: The Management Revolution,” by Andrew McAfee and Erik Brynjolfsson, pages 61 – 68;“Data Scientist: The Sexiest Job of the 21st Century,” by Thomas H. Davenport and D.J. Patil, pages...

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What is Correctness for Statistical Software?

December 14, 2012
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What is Correctness for Statistical Software?

Introduction A few months ago, Drew Conway and I gave a webcast that tried to teach people about the basic principles behind linear and logistic regression. To illustrate logistic regression, we worked through a series of progressively more complex spam detection problems. The simplest data set we used was the following: This data set has

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