How to select positive values in an R data frame column?

We know that positive values are greater than

df1$x[which(df1$x>0)]

Example1

 Live Demo

set.seed(254)
x<−rnorm(20)
df1<−data.frame(x)
df1

Output

x
1 −0.2581511
2 1.5986312
3 0.1347109
4 −0.4816860
5 1.0202752
6 0.2968755
7 −0.1281462
8 1.6107106
9 −1.9545718
10 0.3993334
11 −0.4458160
12 0.5535872
13 1.6401329
14 −0.2909519
15 −0.1275311
16 0.5795695
17 −0.7438926
18 1.2381494
19 0.3837225
20 0.9689413

Example

df1$x[which(df1$x>=0)]

Output

[1] 1.5986312 0.1347109 1.0202752 0.2968755 1.6107106 0.3993334 0.5535872
[8] 1.6401329 0.5795695 1.2381494 0.3837225 0.9689413

Example2

 Live Demo

y<−rnorm(20)
df2<−data.frame(y)
df2

Output

y
1 1.53798786
2 −0.85463326
3 2.39444451
4 0.82559418
5 −2.22197322
6 −1.04243823
7 −0.04693054
8 −0.68691236
9 −1.63040923
10 −1.42408865
11 1.79834289
12 −0.43978051
13 0.47706345
14 0.59884206
15 −0.69136846
16 0.22906493
17 −0.26332146
18 0.29536361
19 −1.24096107
20 0.04963628

Example

df2$y[which(df2$y>=0)]

Output

[1] 1.53798786 2.39444451 0.82559418 1.79834289 0.47706345 0.59884206 0.22906493
[8] 0.29536361 0.04963628

Example3

 Live Demo

z<−sample(−2:2,20,replace=TRUE)
df3<−data.frame(z)
df3

Output

z
1 −2
2 2
3 0
4 −2
5 −2
6 −2
7 0
8 −2
9 −1
10 −2
11 0
12 −2
13 0
14 2
15 1
16 1
17 1
18 0
19 1
20 −2

Example

df3$z[which(df3$z>=0)]

Output

[1] 2 0 0 0 0 2 1 1 1 0 1