Repeat data frames in R

Briefly introduce how to create data frames with repeated suffixes in R

Sometimes, we want to create some data frames with a fixed prefix and a range of numbers. For example, we want to create 10 data frames with names df1, df2, …, df10.

We have two ways to do this.

1. One list: create a list of data frames and store them into a list df_list.
2. Individual dataframe: create 10 data frames with names df1, df2, …, df10 directly.

One list

Firstly, let’s try to create a list of data frames and store them into a list df_list.

library(dplyr)

num <- 1:10

# Create an empty list
df_list <- list()

# Loop through the numbers
for (i in num) {
  # suppose we have different values for x and y
  temp <- data.frame(x = rnorm(10), y = rnorm(10)) %>%
    # Add a column with the current number
    mutate(id = i)
  # Add the data frame to the list
  df_list[[i]] <- temp
}

Then, we can use dplyr to transform the list to a dataframes by using bind_rows.

df <- bind_rows(df_list)

head(df)

A data.frame: 6 x 3

	x <dbl>	y <dbl>	id <int>
1	-0.4229988	-0.2171858	1
2	1.5798157	0.9990500	1
3	-0.1763058	-1.1700267	1
4	0.5552782	-0.4305593	1
5	0.2594807	1.3306744	1
6	0.5152127	0.4716893	1

Individual dataframe

Secondly, let’s try to create 10 data frames with names df1, df2, …, df10 directly.

Then, we can use dplyr to transform the dataframes to a dataframes by using bind_rows.

num <- 1:10

for (i in num) {
  # use assign to create a new variable.names
  assign(paste0("df_", i), data.frame(x = rnorm(10), y = rnorm(10)))
}

# List all the data frames
ls(pattern = "df_")

1. ‘df_1’
2. ‘df_10’
3. ‘df_2’
4. ‘df_3’
5. ‘df_4’
6. ‘df_5’
7. ‘df_6’
8. ‘df_7’
9. ‘df_8’
10. ‘df_9’
11. ‘df_list’

If you want to create a list to store all these variables, we can use get function to get the variable by its name.

# For example, we want to store in df_list2

df_list2 <- list()

for (i in num) {
  # use assign to create a new variable.names
  df_list2[[i]] <- get(paste0("df_", i))
}