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POApplying functions to dataframe or multiple lists
 

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    <p><em>Edit as Per the comments:</em> The OP would like to calculate: </p> <pre><code>(100 * (1 - 10 ^ - (Do - Do[Do==0] )) ⎞ (1 - 10 ^ - (Do[Do==100] - Do[Do==0]) - Do </code></pre> <p>For each combination of <code>Cl</code>, <code>In</code>, <code>Sa</code> in the <code>data.frame</code><br> <em>-RS</em></p> <hr> <p>I am trying to apply a function, called dG, to a dataframe. Since the function's arguments length differ recycling produced unpredictable results.</p> <p>To rectify this issue I separated the dataframe into lists and tried to apply the dG function (below) to each list after identifing each list with a function called 'ids'.</p> <ul> <li>Please feel free to suggest a different solution. FYI, my specific requests start with bullet points </li> </ul> <p>Please let me start by providing synthetic data that shows the issues:</p> <pre><code>Do &lt;- rep(c(0,2,4,6,8,10,15,20,30,40,45,50,55,60,65,70,80,85,90,92,94,96,98,100), each=16,times=16) Cl &lt;- rep(c("K", "Y","M","C"), each= 384, times=4) In &lt;- rep(c("A", "S"), each=3072) Sa &lt;- rep(c(1,2), each=1536) Data &lt;- rnorm(6144) DataFrame &lt;- cbind.data.frame(Do,Cl,In,Sa,Data); head(DataFrame) rm(Do,Cl,In,Sa,Data) attach(DataFrame) DFSplit &lt;- split(DataFrame[ , "Data"], list(Do, Cl, In, Sa)) </code></pre> <p>The function 'ids' is a helper function that identifies the lists names</p> <pre><code>ids &lt;- function(Do, Cl, In, Sa){ grep( paste( "^" , Do, "\\.", Cl, "\\.", In, "\\.", Sa,sep=""), names(DFSplit), value = TRUE)} mapply(ids, Do, Cl, In, Sa, SIMPLIFY = FALSE) </code></pre> <p>The above mapply produces 6144 lists. If you look at the mapply output you will notice that there is 384 unique list names but each is repeated 16 times 384*16=6144.</p> <ul> <li>How can I change the 'ids' function so that mapply doesn't repeat the same name 16 times.</li> </ul> <p>As an ugly and highly costly solution I used unique; I need a better fundamental solution.</p> <pre><code>unique(mapply(ids, Do, Cl, In, Sa, SIMPLIFY = FALSE)) </code></pre> <p>The dG function is the one that I want to operates on each of the 'DFSplit' lists. It has the same issue as the previous ids function. It uses the ids function as an input.</p> <pre><code>dG &lt;- function(Do,Cl, In, Sa){ dg &lt;- 100* (1-10^-( DFSplit[[ids(Do, Cl, In, Sa)]] - DFSplit[[ids(0, Cl, In, Sa)]])) / (1-10^-( DFSplit[[ids(100, Cl, In, Sa)]] - DFSplit[[ids(0, Cl, In, Sa)]])) - Do dg} </code></pre> <p>I tried to use dG as follows and it is not what I want.</p> <pre><code>dG(Do,Cl, In, Sa) </code></pre> <p>It only evaluated the LAST part of the dG function (- Do) plus this warning</p> <p>In grep(paste("^", unique(Do), "\.", unique(Cl), "\.", unique(In), : argument 'pattern' has length > 1 and only the first element will be used</p> <ul> <li>Can you suggest a modification to the dG function</li> </ul> <p>Then I tried mapply</p> <pre><code>mapply(dG, Do, Cl, In, Sa, SIMPLIFY = FALSE) </code></pre> <p>mapply correctly evaluated the function with my data. mapply produces 6144 lists. You will notice that the mapply output is basically 384 unique lists, each repeated 16 times 384*16=6144.</p> <ul> <li>How can I modify the dG function to get rid of the useless and time consuming repetition? </li> </ul> <p>My thought would be:</p> <ol> <li>eliminate the repetition in my first function 'ids', which I do not know how to do .</li> <li><p>change the arguments of the second function so the arguments' lengths would be 384. Maybe use the names of the lists as an input argument. which I do not know how.</p></li> <li><p>Change the formula dG and not use (Do, Cl, In, Sa) arguments since each one has a length of 6144 </p></li> </ol>
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    1. COYour code returns `Error: object 'DFSplit' not found`. How about you drastically simplify this into something that is not 384 unique elements long, but more like 3 elements long so people can see what you're actually trying to do.
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      1. USChase
    2. CO@Chase, `DFSplit` is here. http://stackoverflow.com/questions/15449612/why-does-mapply-repeat-the-same-list-multiple-times OP probably still has it in the env and hence overlooking the error
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      1. USRicardo Saporta
    3. COSorry Chase, that what I get from copy/paste. It is correct now
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