store each variable into a list element

Question

I have this df.

Date <- c("2020-10-01", "2020-10-02", "2020-10-03", "2020-10-04", 
          "2020-10-01", "2020-10-02", "2020-10-03", "2020-10-04",
          "2020-10-01", "2020-10-02", "2020-10-03", "2020-10-04")

Country <- c("USA", "USA", "USA", "USA", 
 "Mexico", "Mexico", "Mexico", "Mexico",
 "Japan", "Japan", "Japan","Japan")

Value_A <- 1:12
Value_B <- 10:21

   Date     Country   Value_A   Value_B
   <date>     <chr>     <int>   <int>
 1 2020-10-01 USA           1      10
 2 2020-10-02 USA           2      11
 3 2020-10-03 USA           3      12
 4 2020-10-04 USA           4      13
 5 2020-10-01 Mexico        5      14
 6 2020-10-02 Mexico        6      15
 7 2020-10-03 Mexico        7      16
 8 2020-10-04 Mexico        8      17
 9 2020-10-01 Japan         9      18
10 2020-10-02 Japan        10      19
11 2020-10-03 Japan        11      20
12 2020-10-04 Japan        12      21

What I want is break this df into n parts, each part being a country. Something like:

list <- list(df[1:4,], df[5:8,], df[9:12,])

ps: for my purposes, the dataframes should stay "long".

ps2: I simplified the df, I have like 50 countries.

I appreciate it if someone can help :)

score 1 · Accepted Answer · answered Nov 05 '20 at 16:07

You can use split.data.frame from base R.

df <- data.frame(Date = Date, Country = Country, Value_a = Value_A, Value_b= Value_B)

>split.data.frame(df,df$Country)
$Japan
         Date Country Value_a Value_b
9  2020-10-01   Japan       9      18
10 2020-10-02   Japan      10      19
11 2020-10-03   Japan      11      20
12 2020-10-04   Japan      12      21

$Mexico
        Date Country Value_a Value_b
5 2020-10-01  Mexico       5      14
6 2020-10-02  Mexico       6      15
7 2020-10-03  Mexico       7      16
8 2020-10-04  Mexico       8      17

$USA
        Date Country Value_a Value_b
1 2020-10-01     USA       1      10
2 2020-10-02     USA       2      11
3 2020-10-03     USA       3      12
4 2020-10-04     USA       4      13

score 0 · Answer 2 · answered Nov 05 '20 at 16:05

Does this work:

df
         Date Country Value_A Value_B
1  2020-10-01     USA       1      10
2  2020-10-02     USA       2      11
3  2020-10-03     USA       3      12
4  2020-10-04     USA       4      13
5  2020-10-01  Mexico       5      14
6  2020-10-02  Mexico       6      15
7  2020-10-03  Mexico       7      16
8  2020-10-04  Mexico       8      17
9  2020-10-01   Japan       9      18
10 2020-10-02   Japan      10      19
11 2020-10-03   Japan      11      20
12 2020-10-04   Japan      12      21
list <- df %>% split(df$Country)
list
$Japan
         Date Country Value_A Value_B
9  2020-10-01   Japan       9      18
10 2020-10-02   Japan      10      19
11 2020-10-03   Japan      11      20
12 2020-10-04   Japan      12      21

$Mexico
        Date Country Value_A Value_B
5 2020-10-01  Mexico       5      14
6 2020-10-02  Mexico       6      15
7 2020-10-03  Mexico       7      16
8 2020-10-04  Mexico       8      17

$USA
        Date Country Value_A Value_B
1 2020-10-01     USA       1      10
2 2020-10-02     USA       2      11
3 2020-10-03     USA       3      12
4 2020-10-04     USA       4      13

store each variable into a list element

2 Answers2