[datatable-help] data.table on existing data.frame list

[Matthew Dowle]

Assuming fread with autostart=40 now works, then quick pseudo might be :

big = rbindlist(lapply(fileNameVector, fread, autostart=40))
big[,y:=y+shift]
big[,shift:=NULL]

Matthew


On 06/08/13 01:35, iembry wrote:
> Hi, thank you for the advice.
>
> I'll keep your suggestion in mind for some other projects, but for this
> project I'm going to have to use read.table and then convert the data.frame
> to data.table as I have over 1000 files that I'm processing. It has not
> taken long to process this first small set of around 60 files.
>
> This is the code that has worked for me to alter an existing column and
> delete a column that was no longer needed:
>
> getratingsmore <- lapply(seq_along(dailyvaluesneednew$site_no), function(u)
> data.table(getratings[[u]]))
> getratingsmore <- lapply(seq_along(dailyvaluesneednew$site_no), function(u)
> getratingsmore[[u]][, y:=y+shift])
> getratingsmore <- lapply(seq_along(dailyvaluesneednew$site_no), function(u)
> getratingsmore[[u]][, shift:=NULL])
>
> It continues with my initial question that I posed earlier.
>
> Thank you.
>
> Irucka
>
>
>
> --
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