Month July 2011

Relatively positioned elements: How to remove white space

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Positioning elements in HTML with CSS creates some problems when rendering the elements to be presented on a website. For example I came across this common problem with relatively positioned elements:

if you relatively position an element an empty space is created in the place where the element was supposed to normally appear

So how can we remove this white gap?

In order to examine this issue let us create an html page with 3 divs. One outer div which includes 2 other divs (div A and div B) and some text that follows the outer div. You can use the following html and css code to reproduce the result presented in the following image. I have chosen to set the background-color of the divs so we can easily identify them.

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Boxplots using R – Multiple values

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(This post explains how to use R to create multiple boxplots in the same graph)

If you have been using R with Rcmdr and have taken a look at the boxplots that you can create with it, then you already know that there are not many options that you can set for the plots. You can only create a boxplot based on one variable from your active dataset (variables with data that you have loaded in your current workspace).

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PostgreSQL pattern matching indexes

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The two basic types of indexes in PostgreSQL are B-trees and Hash. Personally I have only used the B-trees, but recently a friend of mine asked me a question about the way PostgreSQL handles indexes on text fields internally. The question was: “Assume that you have created an index on a varchar field and then you issue a query to retrieve some results. Does your query use the index with the LIKE operator?”

The answer to that actually was No.

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