How to loop through a vector of data frame names to print first columns of the df's?

Question

so x is a vector. i am trying to print the first col of df's name's saved in the vector. so far I have tried the below but they don't seem to work.

x = (c('Ethereum,another Df..., another DF...,'))

for (i in x){
  print(i[,1])
}

sapply(toString(Ethereum), function(i) print(i[1]))

Not really clear what you need. Please give an example with expected output — Sotos, Jun 17 '20 at 14:34
imagine x is vector where each item is a name of a data frame. now I want to print the first colm of each data frame. i would have to go df[,1] to print for each one. now imagine the vector has 100 data frame names. how would you print the first colm of each? I hope that makes sense. — Adetya Aggarwal, Jun 17 '20 at 14:39
Your vector is a single string not a vector. Likely something like `strsplit(',', x)[[1]][1]` is what you're seeking. Or `get(strsplit(',', x)[[1]][1])[, 1]` — Oliver, Jun 17 '20 at 14:40

score 2 · Accepted Answer · answered Jun 17 '20 at 15:14

2

You can try this

x <- c('Ethereum','anotherDf',...)

for (i in x){
  print(get(i)[,1])
}

answered Jun 17 '20 at 15:14

englealuze

Geez get(i) ...dang, y didnt i think of that. your kung-fu is strong. thank you very much. – Adetya Aggarwal Jun 18 '20 at 08:37

score 1 · Answer 2 · answered Jun 17 '20 at 15:07

1

You can use mget to get data in a list and using lapply extract the first column of each dataframe in the list.

data <- lapply(mget(x), `[`, 1)
#Use `[[` to get it as vector. 
#data <- lapply(mget(x), `[[`, 1)

2 Answers2