Filter functio to heatmaps

[jessybbio]

Hello,

somebody know some any filter function to heatmaps? I did a heatmap using a datatable with 100 rows informations. But I want to show only 30 rown in my heatmap. How can I filter this informations?

Thanks

[technocrat]

suppressPackageStartupMessages(library(dplyr))
mtcars %>% filter(mpg > 20)
#>     mpg cyl  disp  hp drat    wt  qsec vs am gear carb
#> 1  21.0   6 160.0 110 3.90 2.620 16.46  0  1    4    4
#> 2  21.0   6 160.0 110 3.90 2.875 17.02  0  1    4    4
#> 3  22.8   4 108.0  93 3.85 2.320 18.61  1  1    4    1
#> 4  21.4   6 258.0 110 3.08 3.215 19.44  1  0    3    1
#> 5  24.4   4 146.7  62 3.69 3.190 20.00  1  0    4    2
#> 6  22.8   4 140.8  95 3.92 3.150 22.90  1  0    4    2
#> 7  32.4   4  78.7  66 4.08 2.200 19.47  1  1    4    1
#> 8  30.4   4  75.7  52 4.93 1.615 18.52  1  1    4    2
#> 9  33.9   4  71.1  65 4.22 1.835 19.90  1  1    4    1
#> 10 21.5   4 120.1  97 3.70 2.465 20.01  1  0    3    1
#> 11 27.3   4  79.0  66 4.08 1.935 18.90  1  1    4    1
#> 12 26.0   4 120.3  91 4.43 2.140 16.70  0  1    5    2
#> 13 30.4   4  95.1 113 3.77 1.513 16.90  1  1    5    2
#> 14 21.4   4 121.0 109 4.11 2.780 18.60  1  1    4    2

^{Created on 2020-04-07 by the reprex package (v0.3.0)}