How to find the mean of list elements in R?

To find the mean of list elements we need to unlist those elements. For example, if we have a list named as List that contains three elements of equal or different sizes such element1, element2, and element3 then we can find the mean of all the list elements by using mean(unlist(List)).

Example1

List1<−list(x1=rnorm(20,5,1),x2=rexp(20,1.5),x3=runif(20,1,5),x4=rpois(20,5))
List1

Output

$x1
[1] 6.108059 4.547547 4.372156 5.989584 5.511777 4.709440 7.021406 6.039822
[9] 4.543087 4.336187 5.042706 4.706642 4.956130 3.778773 4.132992 3.940984
[17] 6.065076 4.612344 4.920258 4.329872
$x2
[1] 0.53495402 0.02912564 0.36639652 0.24274400 0.39298863 0.19216387
[7] 0.28707176 0.60966760 0.12513682 0.32347674 0.84902529 0.81149732
[13] 0.37236099 0.48662762 0.23458569 1.64478209 2.10184808 1.27785900
[19] 0.93100703 0.87303565
$x3
[1] 1.912571 4.163985 3.969263 2.059990 1.199151 3.909256 1.554315 2.895359
[9] 2.086084 2.445037 2.576525 3.065689 3.300594 4.653713 3.849018 2.128604
[17] 3.972365 2.346908 1.345889 1.548029
$x4
[1] 7 4 4 2 5 5 5 6 4 6 7 4 3 7 9 4 2 6 4 6
mean(unlist(List1))
[1] 3.341669

Example2

 Live Demo

List2<−list(y1=rpois(25,5),y2=rpois(25,10),y3=rpois(25,3),y4=rpois(25,2),y5=rpois(25,12),y6=rpois(25,8))
List2

Output

$y1
[1] 5 8 1 7 9 3 4 4 6 3 3 5 2 6 6 5 7 4 3 7 4 2 4 4 1
$y2
[1] 6 9 16 12 9 14 8 5 9 11 14 10 18 9 10 6 5 9 11 9 8 11 8 12 8
$y3
[1] 1 3 3 3 9 6 0 3 2 6 2 2 4 1 1 2 4 1 3 2 1 5 3 5 2
$y4
[1] 1 3 0 1 0 0 0 2 2 2 1 2 1 1 5 0 1 2 3 1 3 3 1 1 3
$y5
[1] 7 17 11 15 9 12 9 15 11 9 12 13 8 14 13 15 10 12 12 11 11 7 11 9 20
$y6
[1] 7 8 5 8 6 12 10 7 11 15 7 7 7 17 7 11 4 5 15 7 4 5 9 13 8
mean(unlist(List2))
[1] 6.54

Example3

 Live Demo

List3<−list(z1=sample(0:2,50,replace=TRUE),z2=sample(1:5,50,replace=TRUE),z3=sample(1:10,50,replace=TRUE),z4=sample(11:20,50,replace=TRUE),z5=sample(1:100,20))
List3

Output

$z1
[1] 1 1 2 0 1 0 2 1 0 1 2 1 1 1 2 0 0 0 0 2 2 2 0 2 0 1 1 2 1 2 0 0 1 0 0 2 0 2
[39] 2 2 1 1 0 0 1 2 0 1 2 1
$z2
[1] 2 2 4 3 4 4 4 2 2 5 5 3 1 2 1 3 1 1 5 4 5 2 2 2 5 4 5 4 1 1 3 2 2 2 5 3 4 4
[39] 3 1 2 5 2 1 5 1 3 5 3 1
$z3
[1] 2 1 6 6 9 3 10 5 3 2 7 3 9 1 7 7 9 3 10 6 9 6 7 1 2
[26] 2 7 8 9 9 10 10 4 6 9 1 4 4 1 3 6 7 5 1 6 4 7 9 7 8
$z4
[1] 14 20 12 19 20 20 19 14 19 16 14 15 18 19 18 16 17 16 15 19 15 15 18 16 16
[26] 16 13 13 19 19 18 12 19 14 11 11 16 16 17 17 11 11 12 16 18 14 12 12 14 16
$z5
[1] 84 3 91 98 8 26 5 62 77 79 44 80 95 22 33 94 48 100 18
[20] 82
mean(unlist(List3))
[1] 10.96364

Example4

 Live Demo

List4<−list(a1=rlnorm(30,20,2),a2=rlnorm(30,40,3.5),a3=rlnorm(30,32,4.87),a4=rlnorm(30,25,2))
List4

Output

$a1
[1] 71542867 3802528183 824955139 537941797 319344620 9780278
[7] 412319119 3651501904 157606770 23725836 160733494 120731549
[13] 7069722553 25051170 541634971 75770086507 1832990477 1475938038
[19] 49199098 5368002989 11307747 52684854 1292534007 433447010
[25] 875482499 113172333 230498945 4929889507 4141435472 703825036
$a2
[1] 1.877107e+14 2.945731e+18 7.871179e+17 2.734189e+18 6.543502e+15
[6] 7.634623e+19 1.119141e+18 6.297200e+15 8.668692e+18 1.974060e+19
[11] 5.513059e+18 7.012868e+14 6.418158e+15 3.669615e+17 7.844477e+17
[16] 1.071829e+14 1.846123e+19 3.174034e+15 2.965029e+19 1.611821e+18
[21] 3.977186e+17 5.586130e+18 3.497191e+17 3.341409e+18 4.465099e+20
[26] 2.118766e+18 2.937740e+17 1.212326e+16 3.861193e+17 1.842242e+16
$a3
[1] 2.360510e+13 4.108881e+12 2.561652e+15 3.753383e+14 8.076318e+13
[6] 1.119506e+12 2.409259e+12 8.971752e+12 2.224645e+14 9.817681e+15
[11] 2.081065e+12 2.216867e+14 1.323823e+14 1.271452e+14 1.744322e+15
[16] 1.157680e+18 4.779613e+11 4.156495e+17 2.361336e+14 1.040876e+14
[21] 2.130798e+15 3.491057e+13 3.638596e+12 7.101385e+12 9.217809e+11
[26] 5.588433e+12 1.319278e+15 9.346423e+11 2.446196e+12 1.985828e+16
$a4
[1] 3.338469e+10 5.547337e+11 5.587813e+10 7.720164e+10 6.328412e+11
[6] 6.939032e+09 8.160043e+09 1.367509e+12 2.770085e+11 4.999626e+11
[11] 2.993918e+10 4.003077e+10 1.966285e+12 4.918578e+09 1.110343e+11
[16] 1.221764e+10 2.352072e+09 3.829187e+09 4.752032e+11 3.299800e+11
[21] 2.154089e+10 1.607422e+10 2.489736e+09 9.573338e+09 1.438301e+10
[26] 1.564655e+10 7.064011e+10 1.458467e+11 1.362668e+08 1.376267e+12
mean(unlist(List4))
[1] 5.244828e+18