I have n number of data.frame i would like to add column to all data.frame
a <- data.frame(1:4,5:8)
b <- data.frame(1:4, 5:8)
test=ls()
for (j in test){
j = cbind(get(j),IssueType=j)
}
Problem that i'm running into is
j = cbind(get(j),IssueType=j)
because it assigns all the data to j instead of a, b.
As commented, it's mostly better to keep related data in a list structure. If you already have the data.frames in your global environment and you want to get them into a list, you can use:
dflist <- Filter(is.data.frame, as.list(.GlobalEnv))
This is from here and makes sure that you only get data.frame objects from your global environment.
You will notice that you now already have a named list:
> dflist
# $a
# X1.4 X5.8
# 1 1 5
# 2 2 6
# 3 3 7
# 4 4 8
#
# $b
# X1.4 X5.8
# 1 1 5
# 2 2 6
# 3 3 7
# 4 4 8
So you can easily select the data you want by typing for example
dflist[["a"]]
If you still want to create extra columns, you could do it like this:
dflist <- Map(function(df, x) {df$IssueType <- x; df}, dflist, names(dflist))
Now, each data.frame in dflist has a new column called IssueType:
> dflist
# $a
# X1.4 X5.8 IssueType
# 1 1 5 a
# 2 2 6 a
# 3 3 7 a
# 4 4 8 a
#
# $b
# X1.4 X5.8 IssueType
# 1 1 5 b
# 2 2 6 b
# 3 3 7 b
# 4 4 8 b
In the future, you can create the data inside a list from the beginning, i.e.
dflist <- list(
a = data.frame(1:4,5:8)
b = data.frame(1:4, 5:8)
)
To create a list of your data.frames do this:
a <- data.frame(1:4,5:8); b <- data.frame(1:4, 5:8); test <- list(a,b)
This allows you to us the lapply function to perform whatever you like to do with each of the dataframes, eg:
out <- lapply(test, function(x) cbind(j))
For most data.frame operations I recommend using the packages dplyr and tidyr.
wooo wooo
here is answer for the issue helped by @docendo discimus
Created Dataframe
a <- data.frame(1:4,5:8) b <- data.frame(1:4, 5:8)
Group data.frame into list
dflist <- Filter(is.data.frame, as.list(.GlobalEnv))
Add's extra column
dflist <- Map(function(df, x) {df$IssueType <- x; df}, dflist, names(dflist))
unstinting the data frame
list2env(dflist ,.GlobalEnv)
listand uselapplyto to loop over all of them and create new columnsaandb(the names of the data.frames)?