Using a loop to create multiple dataframes from a single dataset

Question

Quick question for you. I have the following:

a <- c(1,5,2,3,4,5,3,2,1,3)
b <- c("a","a","f","d","f","c","a","r","a","c")
c <- c(.2,.6,.4,.545,.98,.312,.112,.4,.9,.5)
df <- data.frame(a,b,c)

What i am looking to do is utilize a for loop to create multiple data frames from rows based on the column contents of column B (i.e. a df for the "a," the "d," and so on).

At the same time, I would also like to name the data frame based on the corresponding value from column B (df will be named "a" for the data frame created from the "a."

I tried making it work based off the answers provided here Using a loop to create multiple data frames in R but i had no luck.

If it helps, I have variables created with levels() and nlevels() to use in the loop to keep it scalable based on how my data changes. Any help would be much appreciated.

Thanks!

It's often better to not split your data like this, but instead use tools like dplyr's group_by when you want to do separate calculations for each b group. — Marius
– Marius, Commented Jul 7, 2017 at 0:04

JdeMello · Accepted Answer · 2017-07-07 11:28:47Z

3

This should do:

require(dplyr)

df$b <- as.character(df$b)

col.filters <- unique(df$b) 

lapply(seq_along(col.filters), function(x) {
  filter(df, b == col.filters[x])
  }
  ) -> list

names(list) <- col.filters

list2env(list, .GlobalEnv)

Naturally, you don't need dplyr to do this. You can just use base syntax:

df$b <- as.character(df$b)

col.filters <- unique(df$b) 

lapply(seq_along(col.filters), function(x) {
  df[df[, "b"] == col.filters[x], ]
  }
  ) -> list

names(list) <- col.filters

list2env(list, .GlobalEnv)

But I find dplyrmuch more intuitive.

Cheers

edited Jul 7, 2017 at 11:28

answered Jul 7, 2017 at 1:18

JdeMello

1,72815 silver badges24 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

JdeMello Over a year ago

@d.b 's example is much more elegant IMO.

AdeliciousNom Over a year ago

Thanks so much! I appreciate the two ways to go about it; i had never thought about using dplyr :|

Collectives™ on Stack Overflow

Using a loop to create multiple dataframes from a single dataset

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related