CODEWITHSUNDEEP
rlistdataframelapply
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Reputation: 421

Replacing elements of a list with those from another list based on name

I'm trying to use the named index to replace some elements of a list.

I have three lists:

My objective is to replace the old elements in Superset with the corresponding ones from Subset where Name(Subset) == Name(Superset).

Example Code (Edited for correctness):

# Setting things up
Superset <- list(1, 2, 3, 4)
names(Superset) <- c("a", "b", "c", "d")

Subset <- list(5, 6)
names(Subset) <- c("b", "c") # or any names from Superset

SubsetNames <- as.list(names(Subset))

I have tried things like this:

lapply(SubsetNames, FUN=function(x) Superset[[x]] <- Subset[[x]])

And:

Superset[SubsetNames] <- Subset

I even tried to construct a for-loop with a counter however this is not a working solution in my scenario.

In reality, Superset is a list of dataframes, each of which has almost 90k datapoints in 117 columns. Some of those dataframes need some tweaking. I have code which successfully extracts a list of the ones needing tweaking and tweaks them... now I just need to put them back.

Your help much appreciated! Thank you!

Upvotes: 3

Views: 1071

Answers (2)

akrun
akrun

Reputation: 887213

We can use the names of the 'Subset' to subset the 'Superset' and assign it to values of 'Subset'

Superset[names(Subset)] <- Subset
Superset
#$a
#[1] 1

#$b
#[1] 5

#$c
#[1] 6

#$d
#[1] 4

The list creation seems to be faulty. It would be as.list

Superset <- as.list(1:4)

It will return a list of length 4 as opposed to length 1 with list(1:4)

Upvotes: 2

MrFlick
MrFlick

Reputation: 206253

If you want to change for every value in Subset, you could just do 

modifyList(Superset, Subset)

or if you are just updating a smaller set of values from subset

modifyList(Superset, Subset[SubsetNames])

Upvotes: 1

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