Re: [R] help with loop over data frame
Try this: DF[c(FALSE, tail(DF$Open, -1) head(DF$High, -1)), ] or using zoo objects just compare the Open to the reverse lag of the High. Lines - Date Open HighLowClose 1/15/2000 10 11 8 10 1/16/2000 12 12 10 11 1/17/2000 12 12 10 11 library(zoo) z - read.zoo(textConnection(Lines), header = TRUE, format = %m/%d/%Y) z[ z[, Open] lag(z[, High],-1), ] On 2/18/07, Dr Remo Sammassimo [EMAIL PROTECTED] wrote: Dear List, This may be the fifth time Ive tried to send this to the list so apologies if there are multiple emails. I need some help getting started with this problem. I have a data frame containing a year of daily stock prices in the following format: Date Open HighLowClose 1/15/2000 10 11 8 10 1/16/2000 12 12 10 11 etc.. I want to create a new data frame which shows only the rows where the column value Open for 'today' is higher than the column value High for the previous day (previous row). How do I loop over each day accessing values from different rows and columns, as is needed here? I have tried 'if' statements but none have worked. Any help appreciated. Regards, Alf Sammassimo Melbourne,Australia __ R-help@stat.math.ethz.ch 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. __ R-help@stat.math.ethz.ch 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.
[R] help with loop over data frame
Dear List, This may be the fifth time Ive tried to send this to the list so apologies if there are multiple emails. I need some help getting started with this problem. I have a data frame containing a year of daily stock prices in the following format: Date Open HighLowClose 1/15/2000 10 11 8 10 1/16/2000 12 12 10 11 etc.. I want to create a new data frame which shows only the rows where the column value Open for 'today' is higher than the column value High for the previous day (previous row). How do I loop over each day accessing values from different rows and columns, as is needed here? I have tried 'if' statements but none have worked. Any help appreciated. Regards, Alf Sammassimo Melbourne,Australia __ R-help@stat.math.ethz.ch 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.
Re: [R] help with loop over data frame
On Mon, 2007-02-19 at 13:38 +1100, Dr Remo Sammassimo wrote: Dear List, This may be the fifth time Ive tried to send this to the list so apologies if there are multiple emails. I need some help getting started with this problem. I have a data frame containing a year of daily stock prices in the following format: Date Open HighLowClose 1/15/2000 10 11 8 10 1/16/2000 12 12 10 11 etc.. I want to create a new data frame which shows only the rows where the column value Open for 'today' is higher than the column value High for the previous day (previous row). How do I loop over each day accessing values from different rows and columns, as is needed here? I have tried 'if' statements but none have worked. Any help appreciated. Regards, Alf Sammassimo Melbourne,Australia I think that this should do it. Presuming that your data frame is called 'DF': Rows - which(sapply(seq(along = rownames(DF))[-1], function(x) DF[x, Open] DF[x - 1, High])) + 1 DF.New - DF[Rows, ] The first line sets up a sequence from 2:nrows(DF) and then loops over those indices. The indices are passed as 'x' to the function, which compares the current row (x) Open value with the prior row (x - 1) High value. This returns TRUE or FALSE for each row compared. If TRUE, which() then returns the index of the row plus 1, since we do not want the first row. Those indices are assigned to 'Rows', which is then used to subset 'DF' and create 'DF.New'. Just using the data you have above: DF.New Date Open High Low Close 2 1/16/2000 12 12 1011 See ?which, ?sapply and ?seq HTH, Marc Schwartz __ R-help@stat.math.ethz.ch 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.
