Summing a list of numbers is so common, there is an R function specifically designed for it.
- [Instructor] Matrix math is a complex topic, … and I'm not going to try to explain matrix math … or why you'd need to use it. … If you're using it, you understand it. … The good thing is, is that R provides a rich set of tools … for doing matrix math. … One of them is the ability to find out … if a matrix is symmetrical. … Let's take a look at how issymetric works. … In line three, I create a test matrix. … Let's take a look at that matrix. … In column one, I have one, … and in column one, row two, I have two, … in column two I have three, … and then column two, row two, I have four. … Now, is that symmetrical? … In line five, I ask the question issymetric … to test the matrix, and it comes back … and says, no, that's not. … Well, what does a symmetrical matrix look like? … And in line seven, I've gone ahead and defined one. … You can look at it here, there it is, zero-one-one-zero. … In line nine, I use issymetric on test matrix … to check is test matrix symmetrical? … And issymetric comes back and says, yes, …
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Updated
1/15/2021Released
1/10/2018The five minutes you spend each week will provide you with a building block you can use in the next two hours at work. Review language basics, discover methods to improve existing R code, explore new and interesting features, and learn about useful development tools and libraries that will make your time programming with R that much more productive.
All series code samples can be downloaded at https://github.com/mnr/five-minutes-of-R.Note: Because this is an ongoing series, viewers will not receive a certificate of completion.
Skill Level Intermediate
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plot2m 45s
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cut3m 17s
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cdplot5m 30s
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Plot to file5m 55s
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coplot3m 57s
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cowsay2m 34s
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table2m 46s
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barplot2m 31s
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Pie chart2m 11s
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unlist3m 24s
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Joins: Inner and full3m 3s
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Joins: Left and right2m 13s
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Sets: Equal and in2m 14s
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colors2m 25s
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Dealing with NA6m 1s
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dotchart3m 54s
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fourfoldplot3m 34s
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matplot3m 50s
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dimnames5m 4s
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stemplot2m 57s
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stripchart3m 10s
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Switch2m 16s
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Update your R4m 1s
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heatmap4m 24s
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combine4m 11s
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stopifnot2m 44s
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weighted.mean2m 16s
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chartr3m 50s
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duplicated and unique2m 52s
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load and save4m 23s
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expand.grid2m 55s
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Professional groups2m 26s
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Simplify with c3m 29s
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Logical operators5m 56s
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char.expand3m 57s
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complete.cases3m 16s
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swirl2m 8s
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tryCatch3m 23s
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Double colons3m 5s
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for loop4m 54s
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The 100th episode4m 12s
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while loop4m 18s
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repeat loop4m 14s
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Logic and flow control4m 2s
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matrix, row, and column4m 41s
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issymetric3m 14s
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file.access4m
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file.info4m 1s
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dput and dget4m 35s
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diag2m 52s
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crossprod3m 13s
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upper.tri and lower.tri3m 7s
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message5m 21s
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regexpr5m 45s
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diff4m 50s
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exists1m 58s
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formulas4m 42s
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RPres5m 26s
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lattice: Introduction5m 8s
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lattice: barchart4m 57s
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lattice: panels4m 50s
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par: font, size, color5m 10s
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par: margins6m 21s
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par: pch and points3m 17s
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legend5m 26s
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