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POPutting variables into a list and then getting them back
 

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  1. POPutting variables into a list and then getting them back
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    <p>I have some variables per year, that I want to save to disk to retrieve later. Example:</p> <pre><code>Yr.data &lt;- list() #Year 1 a &lt;- "Year 1" b &lt;- 72 c &lt;- matrix(1, nrow=2, ncol=2) Yr.data[[1]] &lt;- list(a=a, b=b, c=c) #Year 2 a &lt;- "Year 2" b &lt;- 99 c &lt;- matrix(3, nrow=2, ncol=2) Yr.data[[2]] &lt;- list(a=a, b=b, c=c) save (Yr.data, file="Yr_data.Rda") rm(a,b,c,Yr.data) </code></pre> <p>Then later I want to get these variables back, for just one year (second year in example):</p> <pre><code>load("Yr_data.Rda") # Here I want to "unlist" Yr.data[[2]], so I get a, b, c as separate variables print(b) [1] 99 c &lt;- Yr.data[[2]]$c # I know this is a way to do it, but I want it automatically </code></pre> <p>Is there a smart way to do this? Both to save the variables without having to write a=a and so on, and without specifically specifying the variables to get out. The real data I want to save per year is much more complex (spatial objects, dataframes, etc.). I think the solution is simple, but somehow I´m stuck in finding it...</p> <p>Thanks.</p> <p>/Chris</p> <p>Update: Thanks for efforts to help, I really appreciate it. I realize the problem description was not clear enough. For each year (and measurement points) I have for example the variables b and c (but with different values per year and measurement points). These values I need to save to disk for later processing. b can for example be a list() or a SpatialPolygonsDataFrame[] (not sure how to put that into a database). I have other R-scripts to process the variables b and c. The complexity is that I want to save "b" several times in the same file. So I thought it was smart to put it in a list:</p> <pre><code>Yr.data &lt;- list() b &lt;- 17 Yr.data[[1]] &lt;- list(b=b) b &lt;- 42 Yr.data[[2]] &lt;- list(b=b) b &lt;- Yr.data[[1]]$b # b becomes 17 # Or this, in case I need to analyze the second year b &lt;- Yr.data[[2]]$b # b becomes 42 </code></pre> <p>This code does it, but I was hoping to learn a more robust way to do it in case I later add more variables (for example d &lt;- 34 first year and d &lt;- 43 second year).</p> <p>Update 2: I apologize for not explaining clearly enough. I don't want to waste your time. Allow me to try one last time.</p> <p>I have an R-script that process input variables a, b, c. In my examples these variables are simple, but in reality they are more complex objects like sp::SpatialPolygonsDataFrame so I can't put them in dataframes. Sometimes I need to process one set of variables, sometimes another. I thought it good to save these different sets as lists in a list, so if I want to run with first set, I select the first list in the list of lists:</p> <pre><code>Year.I.need.to.analyze &lt;- 1 getAllVariablesInList(Yr.data[[Year.I.need.to.analyze ]]) # creates a, b, c result.I.want &lt;- b * c </code></pre> <p>And when I need to analyze the second year, I just have to change the "Year.I.need.to.analyze" to 2 and run the script again. I would prefer to not save each set in a separate .Rda-file, to avoid "greping" and "paste():ing" on filenames and directories, and also avoid to keep track of which files are needed and so on.</p> <p>I know the example is simple, but the real script must hop between years, create and export plots in between, and so on. I was hoping to automize all that in a robust way. Again sorry for the confusion. After hours of trying to fix this, I realize I might be too tired to explain the question in the best way.</p>
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    1. CO`save(a,b,c,file = "Yr1_data.Rda")` , etc? I can't really tell what you're after here.
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    2. COSorry, I should have mentioned for the reasons of robust code I want all the years in one file. I have need to save data for many years.
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      1. USChris
    3. COI'd probably use an environment instead of a list, but it wouldn't be much different. e.g. `e <- as.environment(Yr.data, recursive=FALSE); ls(e); e$c; with(e, b); get("c", pos=e)`
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