993 search results for "how to import image file to R"

Discovering Argon with the 2-Sample t-Test

Discovering Argon with the 2-Sample t-Test

I learned about Lord Rayleigh’s discovery of argon in my 2nd-year analytical chemistry class while reading “Quantitative Chemical Analysis” by Daniel Harris.  (William Ramsay was also responsible for this discovery.)  This is one of my favourite stories in chemistry; it illustrates how diligence in measurement can lead to an elegant and surprising discovery.  I find

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Getting flexible with SAP HANA

Getting flexible with SAP HANA

Most of you might not be aware of a feature introduced on SAP HANA SPS5. This new feature is called "Flexible Tables", which means that you can define a table that will grow depending on your needs. Let's see an example...You define a table with ID, NA...

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Visualizing Risky Words — Part 2

March 9, 2013
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Visualizing Risky Words — Part 2

This is a follow-up to my Visualizing Risky Words post. You’ll need to read that for context if you’re just jumping in now. Full R code for the generated images (which are pretty large) is at the end. Aesthetics are the primary reason for using a word cloud, though one can pretty quickly recognize what

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Comparing quantiles for two samples

March 8, 2013
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Comparing quantiles for two samples

Recently, for a research paper, I some samples, and I wanted to compare them. Not to compare they means (by construction, all of them were centered) but there dispersion. And not they variance, but more their quantiles. Consider the following boxplot type function, where everything here is quantile related (which is not the case for standard boxplot, see http://freakonometrics.hypotheses.org/4138,...

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Easily plotting grouped bars with ggplot #rstats

March 5, 2013
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Easily plotting grouped bars with ggplot #rstats

Summary This tutorial shows how to create diagrams with grouped bar charts or dot plots with ggplot. The groups can also be displayed as facet grids. Importing the data from SPSS All following examples are based on an imported SPSS … Weiterlesen →

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Load Balanced Parallelization with snowfall

March 5, 2013
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Load Balanced Parallelization with snowfall

For some reason, I didn't notice a few months ago the best way to perform a parallelized version of Lapply with package snowfall. We implemented the parallel version of function lapply with the function sfLapply, in the development of our pipeline p...

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Visualizing neural networks from the nnet package

March 4, 2013
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Visualizing neural networks from the nnet package

Neural networks have received a lot of attention for their abilities to ‘learn’ relationships among variables. They represent an innovative technique for model fitting that doesn’t rely on conventional assumptions necessary for standard models and they can also quite effectively handle multivariate response data. A neural network model is very similar to a non-linear regression

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PCA to PLS modeling analysis strategy for WIDE DATA

March 2, 2013
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PCA to PLS modeling analysis strategy for WIDE DATA

Working with wide data is already hard enough, add to this row outliers and things can get murky fast. Here is an example of an anlysis of a wide data set, 24 rows  x 84 columns. Using imDEV, written in R, to calculate and visualize a principal components analysis (PCA) on this data set. We find that

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Adding Labels to Points in a Scatter Plot in R

Adding Labels to Points in a Scatter Plot in R

What’s the Scatter? A scatter plot displays the values of 2 variables for a set of data, and it is a very useful way to visualize data during exploratory data analysis, especially (though not exclusively) when you are interested in the relationship between a predictor variable and a target variable.  Sometimes, such data come with categorical

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The MaxDiff Killer: Rank-Ordered Logit Models

February 27, 2013
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Compared to MaxDiff (Sawtooth Software), ranked-order logit modeling:simplifies data collection without needing additional software to generate experimental designsreduces respondent burden making the task easier and seemingly ...

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