How to automatically create multiple dataframes from columns of a single dataframe?

Question

my data frame "test" looks like this:

Date                1          2          3
01.01.1985         NA         NA         NA
09.01.1985         NA         NA         NA
17.01.1985 0.05173014 0.04578678 0.04326039
25.01.1985         NA         NA         NA
02.02.1985         NA         NA         NA
10.02.1985 0.05835957 0.05499137 0.05497832

For each column from 1 to n (except for the date column) I want to create 1 to n (in this example 3) dataframes that each contain the date column and another column from 1 to n. Example:

        Date          3
1 01.01.1985         NA
2 09.01.1985         NA
3 17.01.1985 0.04326039
4 25.01.1985         NA
5 02.02.1985         NA
6 10.02.1985 0.05497832

Ideally each new dataframe would be named after its number "n" or something like "new_frame_n". As my whole data frame contains more than a thousand rows (dates) and something around 50 columns (named after 1 to n) i would like to figure out a way to do that automatically. I've tried it in numerous ways, this is what i have so far:

i <- 2 #start at second column
m <- ncol(test) # assign this to length of loop
m

for (i in 2:m) {
    new_frame_[[i-1]] <-  subset(test, select = c(Date, i))
    i <- i+1
}

I've come across this How to create multiple data frames from a huge data frame using a loop? [closed], tried to apply it to my data but it didn't work, so i thought a loop would work. I'm pretty new to r. Thanks a lot!

I recommend using a list l <- lapply(seq_along(df)[-1], function(x) df[, c(1, x)]) if you must have them as separate objects, you can name the list elements, here I name them new_frame_1, _2, _3, and then do list2env(setNames(l, paste0('new_frame_', seq_along(l))), envir = .GlobalEnv) so that now you have three new data frame objects, new_frame_1, new_frame_2, new_frame_3, in your workspace — rawr
– rawr, Commented Mar 1, 2016 at 19:07
thanks for the advice. while looking for solutions i came across a lot of similar questions and basically the people who were answering always recommended to use a list. so i will try that as well. — geopanda1
– geopanda1, Commented Mar 3, 2016 at 8:37

Wyldsoul · Accepted Answer · 2016-03-01 18:30:08Z

2

Try this:

df <- read.table(textConnection("
Date                1          2          3
01.01.1985         NA         NA         NA
09.01.1985         NA         NA         NA
17.01.1985 0.05173014 0.04578678 0.04326039
25.01.1985         NA         NA         NA
02.02.1985         NA         NA         NA
10.02.1985 0.05835957 0.05499137 0.05497832" ) ,header=TRUE)

for ( i in 1:ncol(df[-1])) {
 assign(paste0("new_frame", i), cbind(df[1], df[-1][i])) 
 }

answered Mar 1, 2016 at 18:30

Wyldsoul

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1 Comment

geopanda1 Over a year ago

Thank you, this is exactly what I was looking for.

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