Drawly Random Rows
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Draw Random Subset of
Sample
We have a sample of N individuals in some dataframe. Draw without
replacement a subset \(M<N\) of
rows.
# parameters, it_M < it_N
it_N <- 10
it_M <- 5
# Draw it_m from indexed list of it_N
set.seed(123)
ar_it_rand_idx <- sample(it_N, it_M, replace=FALSE)
# dataframe
df_full <- as_tibble(matrix(rnorm(4,mean=0,sd=1), nrow=it_N, ncol=4)) %>% rowid_to_column(var = "ID")
# random Subset
df_rand_sub_a <- df_full[ar_it_rand_idx,]
# Random subset also
df_rand_sub_b <- df_full[sample(dim(df_full)[1], it_M, replace=FALSE),]
# Print
# Display
kable(df_full) %>% kable_styling_fc()
|
ID
|
V1
|
V2
|
V3
|
V4
|
|
1
|
0.1292877
|
0.4609162
|
0.1292877
|
0.4609162
|
|
2
|
1.7150650
|
-1.2650612
|
1.7150650
|
-1.2650612
|
|
3
|
0.4609162
|
0.1292877
|
0.4609162
|
0.1292877
|
|
4
|
-1.2650612
|
1.7150650
|
-1.2650612
|
1.7150650
|
|
5
|
0.1292877
|
0.4609162
|
0.1292877
|
0.4609162
|
|
6
|
1.7150650
|
-1.2650612
|
1.7150650
|
-1.2650612
|
|
7
|
0.4609162
|
0.1292877
|
0.4609162
|
0.1292877
|
|
8
|
-1.2650612
|
1.7150650
|
-1.2650612
|
1.7150650
|
|
9
|
0.1292877
|
0.4609162
|
0.1292877
|
0.4609162
|
|
10
|
1.7150650
|
-1.2650612
|
1.7150650
|
-1.2650612
|
kable(df_rand_sub_a) %>% kable_styling_fc()
|
ID
|
V1
|
V2
|
V3
|
V4
|
|
3
|
0.4609162
|
0.1292877
|
0.4609162
|
0.1292877
|
|
10
|
1.7150650
|
-1.2650612
|
1.7150650
|
-1.2650612
|
|
2
|
1.7150650
|
-1.2650612
|
1.7150650
|
-1.2650612
|
|
8
|
-1.2650612
|
1.7150650
|
-1.2650612
|
1.7150650
|
|
6
|
1.7150650
|
-1.2650612
|
1.7150650
|
-1.2650612
|
kable(df_rand_sub_b) %>% kable_styling_fc()
|
ID
|
V1
|
V2
|
V3
|
V4
|
|
5
|
0.1292877
|
0.4609162
|
0.1292877
|
0.4609162
|
|
3
|
0.4609162
|
0.1292877
|
0.4609162
|
0.1292877
|
|
9
|
0.1292877
|
0.4609162
|
0.1292877
|
0.4609162
|
|
1
|
0.1292877
|
0.4609162
|
0.1292877
|
0.4609162
|
|
4
|
-1.2650612
|
1.7150650
|
-1.2650612
|
1.7150650
|
Random Subset of
Panel
There are \(N\) individuals, each
could be observed \(M\) times, but then
select a subset of rows only, so each person is randomly observed only a
subset of times. Specifically, there there are 3 unique students with
student ids, and the second variable shows the random dates in which the
student showed up in class, out of the 10 classes available.
# Define
it_N <- 3
it_M <- 10
svr_id <- 'student_id'
# dataframe
set.seed(123)
df_panel_rand <- as_tibble(matrix(it_M, nrow=it_N, ncol=1)) %>%
rowid_to_column(var = svr_id) %>%
uncount(V1) %>%
group_by(!!sym(svr_id)) %>% mutate(date = row_number()) %>%
ungroup() %>% mutate(in_class = case_when(rnorm(n(),mean=0,sd=1) < 0 ~ 1, TRUE ~ 0)) %>%
dplyr::filter(in_class == 1) %>% select(!!sym(svr_id), date) %>%
rename(date_in_class = date)
# Print
kable(df_panel_rand) %>% kable_styling_fc()
|
student_id
|
date_in_class
|
|
1
|
1
|
|
1
|
2
|
|
1
|
8
|
|
1
|
9
|
|
1
|
10
|
|
2
|
5
|
|
2
|
8
|
|
2
|
10
|
|
3
|
1
|
|
3
|
2
|
|
3
|
3
|
|
3
|
4
|
|
3
|
5
|
|
3
|
6
|
|
3
|
9
|