[R-sig-Geo] iterative field naming

[Jordan Chamberlin]

Thank you, Edzer, Tom and Tom. Problem solved!

On 11/12/29 6:15 AM, Edzer Pebesma wrote:
> Jordan, please try
>
>     zmbpts[[myfname]]<- extr$band1
>
> On 12/29/2011 12:19 AM, Jordan Chamberlin wrote:
>> Dear people,
>>
>> Apologies in advance for what must be a silly question:  I want to
>> iterative add a field to a dataframe, where the field takes a name that
>> is created as part of the iteration. In the bit of code below, the
>> problem line is "zmbpts$myfname<- extr$band1" : what I want to do is
>> have the value of the string "myfname" be used as the name of the new
>> field (rather than creating a new field called "myfname", which is what
>> I'm doing).
>>
>> for (i in 2000:2009) {
>>      for (j in 1:12) {
>>
>>          #temporarily go to data directory, grab file, then return to
>> working directory
>>          setwd(mydd)
>>          myingrid<- gsub("( )", "", paste("pre", i, "_", j))
>>          tmpgrid<- readGDAL(myingrid)
>>          setwd(mywd)
>>
>>          #create SpatialPixelsDataFrame
>>          spdf<- as(tmpgrid, "SpatialPixelsDataFrame")
>>           #summary(spdf)
>>           #image(spdf, "band1", axes=TRUE, col=terrain.colors(20))
>>
>>          #extract values to points
>>          proj4string(spdf)<-proj4string(zmbpts)
>>          extr = over(zmbpts,spdf)
>>
>>          #add extracted values to SpatialPointsDataFrame
>>          myfname<- gsub("( )", "", paste("y", i, "m", j))
>>          zmbpts$myfname<- extr$band1
>>
>>      }
>> }
>>
>> Thanks for your kind help!  Jordan
>>
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