[R] Defining multiple variables in a loop

[Taylor White]

Thank you gentlemen for pointing me in the right direction.

This code worked nicely:


countries <- list()

for (i in 1:20) {
countries[[i]] = as.matrix(subset(OECDFiscal2, Country == i))
}

Take care,

Taylor

On Sun, Jun 24, 2012 at 3:01 PM, R. Michael Weylandt
<michael.weylandt at gmail.com> wrote:
> To elaborate on what Bert said:
>
> Lists are a variable length data structure which can hold most
> anything (even other lists) in them and are a great way to organize
> the sort of data you're working with. You can think of them as
> "generic vectors." You can assign them names and access/subset them by
> names or by element number. Perhaps most usefully, instead of passing
> all the vectors to a function which may need them, you can simply pass
> the one list object. This will make things much easier to maintain in
> the long run/
>
> Most everything complicated in R like data.frames or model objects are
> internally implemented as lists (with various added features) and they
> [lists] are exceptionally powerful. It will seem like more overhead
> now than the lots-of-simple-vectors approach, but in the long run, it
> will be most certainly worth it.
>
> Best,
> Michael
>
> On Sun, Jun 24, 2012 at 4:30 PM, Bert Gunter <gunter.berton at gene.com> wrote:
>> Standard response: Use lists instead.
>>
>> Read An Intro to R to learn about lists. In fact,read an An Intro to R,
>> full stop ( if you have not already done so).
>>
>> Cheers,
>> Bert
>>
>> On Sun, Jun 24, 2012 at 2:15 PM, Taylor White
>> <taylorgentrywhite at gmail.com>wrote:
>>
>>> Good day,
>>>
>>> For lack of a better solution (or perhaps I am ignorant to something
>>> more elegant), I have been bootstrapping panel data by hand so to
>>> speak and I would like to know if there is a way to define multiple
>>> variables in a loop using the loop variable.  I found a post (here:
>>> https://stat.ethz.ch/pipermail/r-help/2002-October/026305.html ) that
>>> discussed naming multiple variables but it didn't seem to allow me to
>>> define the variables as something more useful.  I tried the code
>>> immediately below (plus some variations) and it just didn't work.
>>>
>>> for (i in 1:20) {
>>> assign(paste("country.", i, sep = "") <- subset(OECDFiscal2, Country == i)
>>> }
>>>
>>>
>>> I included some sample code from what I've been working on below so
>>> one can see how it would be very useful to figure out how to define a
>>> series of variables from cross sectional units from a panel dataset.
>>>
>>>
>>> Any help would be much appreciated.
>>>
>>>
>>> Thanks,
>>>
>>> Taylor White
>>> UCLA
>>>
>>>
>>>
>>> ######Bootstrapping panel data by hand.  Create 4 variables from 3
>>> subsets of the original data. Resample each variable and recombine
>>> into one matrix.
>>>
>>>
>>> plmcoef <- array(0, c(1000, 4)) #creates an empty array to store
>>> regression coefficients
>>> plmfixef <- array(0, c(1000, 3)) #creates an empty array to store
>>> fixed effects intercepts from regressions
>>>
>>>
>>> for (i in 1:1000) {
>>> country1 <- as.data.frame(subset(OECDFiscal2, Country == 1))
>>> country2 <- as.data.frame(subset(OECDFiscal2, Country == 2))
>>> country3 <- as.data.frame(subset(OECDFiscal2, Country == 3))
>>>
>>> exp1 <- as.matrix(sample(country1$lagexpVSgdp, size =
>>> (nrow(country1)), replace = T))
>>> exp2 <- as.matrix(sample(country2$lagexpVSgdp, size =
>>> (nrow(country2)), replace = T))
>>> exp3 <- as.matrix(sample(country3$lagexpVSgdp, size =
>>> (nrow(country3)), replace = T))
>>>
>>> tax1 <- as.matrix(sample(country1$lagtaxVSgdp1, size =
>>> (nrow(country1)), replace = T))
>>> tax2 <- as.matrix(sample(country2$lagtaxVSgdp1, size =
>>> (nrow(country2)), replace = T))
>>> tax3 <- as.matrix(sample(country3$lagtaxVSgdp1, size =
>>> (nrow(country3)), replace = T))
>>>
>>> gdp1 <- as.matrix(sample(country1$yoygdpcapita, size =
>>> (nrow(country1)), replace = T))
>>> gdp2 <- as.matrix(sample(country2$yoygdpcapita, size =
>>> (nrow(country2)), replace = T))
>>> gdp3 <- as.matrix(sample(country3$yoygdpcapita, size =
>>> (nrow(country3)), replace = T))
>>>
>>> unemployment1 <- as.matrix(sample(country1$lagunemployment, size =
>>> (nrow(country1)), replace = T))
>>> unemployment2 <- as.matrix(sample(country2$lagunemployment, size =
>>> (nrow(country2)), replace = T))
>>> unemployment3 <- as.matrix(sample(country3$lagunemployment, size =
>>> (nrow(country3)), replace = T))
>>>
>>> country.year1 <- as.matrix(cbind(country1$Country, country1$Year2))
>>> country.year2 <- as.matrix(cbind(country2$Country, country2$Year2))
>>> country.year3 <- as.matrix(cbind(country3$Country, country3$Year2))
>>>
>>> country1.2 <- as.data.frame(cbind(country.year1, exp1, tax1, gdp1,
>>> unemployment1))
>>> country2.2 <- as.data.frame(cbind(country.year2, exp2, tax2, gdp2,
>>> unemployment2))
>>> country3.2 <- as.data.frame(cbind(country.year3, exp3, tax3, gdp3,
>>> unemployment3))
>>>
>>> data <- as.data.frame(rbind(country1.2, country2.2, country3.2))
>>>
>>> OECDsamplepanel <- pdata.frame(data, index = NULL, drop = F)
>>>
>>> plm <- plm(V5 ~ lag(V6, 1) + V3 + V4 + V5, data = OECDSamplepanel,
>>> model = "within")
>>>
>>> coefficients <- t(as.matrix(plm$coefficients))
>>> fixef <- t(as.matrix(fixef(plm)))
>>>
>>> plmcoef[i, 1:4] = coefficients
>>> plmfixef[i, 1:3] = fixef
>>>
>>> }
>>>
>>> ______________________________________________
>>> 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.
>>>
>>
>>
>>
>> --
>>
>> Bert Gunter
>> Genentech Nonclinical Biostatistics
>>
>> Internal Contact Info:
>> Phone: 467-7374
>> Website:
>> http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm
>>
>>        [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.