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POUpdate Variable within Loop in R
 

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    <p>How should I modify my code to update variables within a loop?</p> <p>Specifically, I want to do something like the following:</p> <pre><code>myMatrix1 &lt;- read.table(someFile) myMatrix2 &lt;- read.table(someFile2) for (i in nrow(myMatrix2)) { myMatrix3 &lt;- myMatrix1[which(doSomeTest),] myMatrix4 &lt;- rep(myMatrix2$header1,nrow(myMatrix1)) myMatrix5 &lt;- rep(myMatrix2$header2, nrow(myMatrix1)) myMatrix6 &lt;- cbind(myMatrix3, myMatrix4, myMatrix5) # *see question } </code></pre> <p>How can I get myMatrix6 to be updated instead of reassigned the product of <code>cbind(myMatrix3, myMatrix4, myMatrix5)</code>? In other words, if the first iteration (i = 1) gave a myMatrix6 of:</p> <pre><code>&gt; 1 1 1 1 &gt; 2 2 2 2 </code></pre> <p>and the second iteration (i = 2) gave myMatrix 6 of:</p> <pre><code>&gt; 3 3 3 3 &gt; 4 4 4 4 </code></pre> <p>how do I get a dataframe(?) of:</p> <pre><code>&gt; 1 1 1 1 &gt; 2 2 2 2 &gt; 3 3 3 3 &gt; 4 4 4 4 </code></pre> <p>UPDATE:</p> <p>I have - thanks to DWin and Timo's suggestions - got the following. However, the following code has taken me about 2 hours to run on my datasets. Are there any ways to make it run any faster??? (without using a more powerful computer I may add)</p> <pre><code># create empty matrix for sedimentation myMatrix6 &lt;- data.frame(NA,NA,NA,NA)[0,] names(myMatrix6) &lt;- letters[1:4] # create empty matrix for bore myMatrix7 &lt;- data.frame(NA,NA,NA,NA)[0,] names(myMatrix7) &lt;- letters[1:4] for (i in 1:nrow(myMatrix2)) { # create matrix that has the value of myMatrix1$begin being # situated between the values of myMatrix2begin[i] and myMatrix2finish[i] myMatrix3 &lt;- myMatrix1[which((myMatrix1$begin &gt; myMatrix2$begin[i]) &amp; (myMatrix1$begin &lt; myMatrix2$finish[i])),] myMatrix4 &lt;- rep(myMatrix2$sedimentation, nrow(myMatrix3)) if (is.na(myMatrix2$boreWidth[i])) { myMatrix5 &lt;- rep(NA, nrow(myMatrix3)) } else if (myMatrix2$boreWidth[i] == 0) { myMatrix5 &lt;- rep(TRUE, nrow(myMatrix3)) } else if (myMatrix2$boreWidth[i] &gt; 0) { myMatrix5 &lt;- rep(FALSE, nrow(myMatrix3)) } myMatrix6 &lt;- rbind(myMatrix6, cbind(myMatrix3, myMatrix4)) myMatrix7 &lt;- rbind(myMatrix7, cbind(myMatrix3, myMatrix5)) } </code></pre>
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    1. COYou nave not made clear what connections these various objects have. Is "someVector" related in some way to "myMatrix1"? Likewise, what is "someArg"? And assignment to "myMatrix2" will replace it, NOT append to it. I suspect you are making incorrect claims about R because it is not someOtherLanguage.
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    2. CO_I suspect you are making incorrect claims about R because it is not someOtherLanguage_ I don't doubt it. That's why I said _seems_. Anyway, thanks for the helpful comment.
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    3. CO@Kaleb I have edited your question to remove the inflammatory wording. Please check for correctness.
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