My question is regards accessing complex lists. I am new to R, but experienced in Java, Python, SQL. I am working with an object: Dataprocess and in it slot: data that is a list. Also I am creating generic functions to perform on the slot: data which is the list. I am working with the Airline dataset - so the data slot is a list of the years 1987, 1988, .. I am trying to perform factor and such operations on the column elements of each year. So - for purposes of this discussion we will refer to the column: dayOfWeek in each of the years. My issue is that while I get to the list I need I cannot directly access the list elements to apply the factor function to. I can print the list directly. I try to explain as follows: ... So the data has several columns. And in the method I can get to a column using: x <- list(lapply(this at data, '[[', ?dayOfWeek?)) print(x) OR print(x[1]) >> gives: [[1]] [[1]]$`1987` [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... print(x[[1]]) >> gives: $`1987` [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... If I do: z <- factor(x) OR z <- factor(x[1]) OR z <- factor(x[[1]]) I get Error in sort.list(y) : 'x' must be atomic for 'sort.list' Have you called 'sort' on a list? ... I have also tried: y <- list(sapply(this at data, '[', ?dayOfWeek?)) print(y) OR print (y[1]) >> gives: [[1]] [[1]]$`1987.dayOfWeek` [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... print(y[[1]]) >> gives: $`1987.dayOfWeek` [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... Again If I do: z <- factor(y) OR z <- factor(y[1]) OR z <- factor(y[[1]]) I get Error in sort.list(y) : 'x' must be atomic for 'sort.list' Have you called 'sort' on a list? I have tried accessing the list directly as y[[1]]$?1987.dayOfWeek? which gives me the list elements. And then factor(y[[1]]$?dayOfWeek?) works fine! Gives me: [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... Levels: 1 2 3 4 5 6 7 But I do not have this flexibility as I am doing the lapply or sapply as part of a for loop. So the functions are really: x <- list(lapply(this at data, '[[', each)) y <- list(sapply(this at data, '[', each)) So it is not possible for me to access in a hard-coded manner as y[[1]]$?1987.dayOfWeek? So I do not understand how to access the list elements directly to apply factor and not just the list. None of the accesses as x, x[1], x[[1]] OR y, y[1] or y[[1]] work. It gives me access to the list for print and such - but not to the list elements to apply factor. The only way to access the list elements directly is by y[[1]]$?1987.dayOfWeek? and then I can factor. However I do not have this option as I am in a loop. I hope I have explained this clearly. If not please let me know and I can try again or post the code. Thank you for your help. Mono -- View this message in context: http://r.789695.n4.nabble.com/Accessing-List-within-a-List-in-a-for-Loop-tp4651086.html Sent from the R help mailing list archive at Nabble.com.
Hello, Mono, your description of your problem is a bit "overwhelming". You might get an answer if you provide (simplified) reproducible code (maybe with example data). I can only guess that -- instead of factor( x[[1]]) -- you maybe should use factor( x[[1]][1]) in some place. Hth -- Gerrit On Tue, 27 Nov 2012, m.dr wrote:> My question is regards accessing complex lists. I am new to R, but > experienced in Java, Python, SQL. > > I am working with an object: Dataprocess and in it slot: data that is a > list. > Also I am creating generic functions to perform on the slot: data which is > the list. > I am working with the Airline dataset - so the data slot is a list of the > years 1987, 1988, .. > I am trying to perform factor and such operations on the column elements of > each year. > So - for purposes of this discussion we will refer to the column: dayOfWeek > in each of the years. > > My issue is that while I get to the list I need I cannot directly access the > list elements to apply the factor function to. I can print the list > directly. I try to explain as follows: > ... > So the data has several columns. And in the method I can get to a column > using: > x <- list(lapply(this at data, '[[', ??dayOfWeek??)) > print(x) OR print(x[1]) >> gives: > [[1]] > [[1]]$`1987` > [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... > > print(x[[1]]) >> gives: > $`1987` > [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... > > If I do: z <- factor(x) OR z <- factor(x[1]) OR z <- factor(x[[1]]) I get > Error in sort.list(y) : 'x' must be atomic for 'sort.list' > Have you called 'sort' on a list? > ... > I have also tried: > y <- list(sapply(this at data, '[', ??dayOfWeek??)) > print(y) OR print (y[1]) >> gives: > [[1]] > [[1]]$`1987.dayOfWeek` > [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... > > print(y[[1]]) >> gives: > $`1987.dayOfWeek` > [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... > > Again If I do: z <- factor(y) OR z <- factor(y[1]) OR z <- factor(y[[1]]) I > get > Error in sort.list(y) : 'x' must be atomic for 'sort.list' > Have you called 'sort' on a list? > > I have tried accessing the list directly as y[[1]]$??1987.dayOfWeek?? which > gives me the list elements. > And then factor(y[[1]]$??dayOfWeek??) works fine! > > Gives me: > [1] 3 4 6 7 1 3 4 5 6 7 1 3 4 6 4 5 ... > Levels: 1 2 3 4 5 6 7 > > But I do not have this flexibility as I am doing the lapply or sapply as > part of a for loop. > So the functions are really: > x <- list(lapply(this at data, '[[', each)) > y <- list(sapply(this at data, '[', each)) > > So it is not possible for me to access in a hard-coded manner as > y[[1]]$??1987.dayOfWeek?? > So I do not understand how to access the list elements directly to apply > factor and not just the list. > None of the accesses as x, x[1], x[[1]] OR y, y[1] or y[[1]] work. > It gives me access to the list for print and such - but not to the list > elements to apply factor. > The only way to access the list elements directly is by > y[[1]]$??1987.dayOfWeek?? and then I can factor. > > However I do not have this option as I am in a loop. > > I hope I have explained this clearly. > If not please let me know and I can try again or post the code. > > Thank you for your help. > > Mono > > > > -- > View this message in context: http://r.789695.n4.nabble.com/Accessing-List-within-a-List-in-a-for-Loop-tp4651086.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > >
Thanks Gerritt. That really helped. I needed the second subscript. And yes I will make my posts simpler next time. -- View this message in context: http://r.789695.n4.nabble.com/Accessing-List-within-a-List-in-a-for-Loop-tp4651086p4651170.html Sent from the R help mailing list archive at Nabble.com.
Two things (at least) to consider if you post again. 1) This is a mailing list and Nabble is a cruel deception. It deludes you into thinking you are communicating effectively with your audience. 2) Much better to look at the results of str(object) than to use print(object) On Nov 28, 2012, at 10:43 AM, m.dr wrote:> Thanks Gerritt. That really helped. I needed the second subscript. > > And yes I will make my posts simpler next time.Not so "simple" as this I hope. Simple has a few meanings and this context-free posting is eliciting the interpretation of "simple" that you probably would like to avoid.>-- David Winsemius, MD Alameda, CA, USA
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