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Data Visualization

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Rick WicklinMarch 9, 2022 1

Did you know that you can use π to partition the positive integers into two disjoint groups? It's not hard. One group is generated by the integer portions of multiples of π. The FLOOR function gives the integer portion of a positive number, so you can write integer that are

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Analytics | Data Visualization | Programming Tips

Rick WicklinJanuary 3, 2022 3

Top 10 posts from The DO Loop in 2021

Last year, I wrote almost 100 posts for The DO Loop blog. My most popular articles were about data visualization, statistics and data analysis, and simulation and bootstrapping. If you missed any of these gems when they were first published, here are some of the most popular articles from 2021:

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Analytics | Data Visualization

Rick WicklinDecember 15, 2021 0

A statistical palette of Christmas colors

Suppose you are creating a craft project for the Christmas holidays, and you want to choose a palette of Christmas colors to give it a cheery holiday appearance. You could use one of the many online collections of color palettes to choose a Christmas-themed palette. However, I didn't want to

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Analytics | Data Visualization

Rick WicklinDecember 13, 2021 5

A principal component analysis of color palettes

In a previous article, I visualized seven Christmas-themed palettes of colors, as shown to the right. You can see that the palettes include many red, green, and golden colors. Clearly, the colors in the Christmas palettes are not a random sample from the space of RGB colors. Rather, they represent

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Data Visualization | Learn SAS

Rick WicklinDecember 8, 2021 4

Visualize palettes of colors in SAS

In data visualization, colors can represent the values of a variable in a choropleth map, a heatmap, or a scatter plot. But how do you visualize a palette of colors from the RGB or hexadecimal values of the colors? One way is to use the HEATMAPDISC subroutine in SAS/IML, which

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Data Visualization | Programming Tips

Rick WicklinNovember 17, 2021 0

The order of vertices on a convex polygon

In a previous article, I showed how to use theCVEXHULL function in SAS/IML to compute the convex hull of a finite set of planar points. The convex hull is a convex polygon, which is defined by its vertices. To visualize the polygon, you need to know the vertices in sequential

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Data Visualization | Learn SAS | Programming Tips

Rick WicklinNovember 15, 2021 10

Two-dimensional convex hulls in SAS

Given a cloud of points in the plane, it can be useful to identify the convex hull of the points. The convex hull is the smallest convex set that contains the observations. For a finite set of points, it is a convex polygon that has some of the points as

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Data Visualization | Learn SAS

Rick WicklinNovember 10, 2021 2

Create a frequency polygon in SAS

I was recently asked how to create a frequency polygon in SAS. A frequency polygon is an alternative to a histogram that shows similar information about the distribution of univariate data. It is the piecewise linear curve formed by connecting the midpoints of the tops of the bins. The graph

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Analytics | Data Visualization

Rick WicklinNovember 8, 2021 0

The normal approximation and random samples of the binomial distribution

Recall that the binomial distribution is the distribution of the number of successes in a set of independent Bernoulli trials, each having the same probability of success. Most introductory statistics textbooks discuss the approximation of the binomial distribution by the normal distribution. The graph to the right shows that the

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Data Visualization | Learn SAS

Rick WicklinNovember 3, 2021 7

Add reference lines to a bar chart in SAS

A SAS programmer asked whether it is possible to add reference lines to the categorical axis of a bar chart. The answer is yes. You can use the VBAR statement, but I prefer to use the VBARBASIC (or VBARPARM) statement, which enables you to overlay a wide variety of graphs

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