Add New Value to Each Element of List in R

Suppose we have a list that contain two elements and we get a new value for both of these elements then the problem of adding those values to the original list arises. This can be done with the help of mapply function. We can append the new values in the original easily but a vector of the new values needs to be created first.

Example1

 Live Demo

List1<−list(x1=rnorm(50),x2=rnorm(50))
new<−list(0.34,0.37)

Adding new values to List1 −

Example

List1<−mapply(append,List1,new,SIMPLIFY=FALSE)
List1

Output

$x1
[1] −0.21433819 0.34745333 −0.91392492 −1.18555411 −0.99932134 −0.57548735
[7] 1.10651668 0.48454439 −0.99232515 −0.99568362 0.23641052 2.67800406
[13] −0.75788305 1.19569169 −1.15838659 0.73623778 −0.17743427 1.30542832
[19] −1.76846085 −0.59177306 0.17272266 −0.63534109 −0.23215985 −1.67575615
[25] 0.59034063 2.52226746 0.40437735 −0.06360738 −0.53810661 −0.04455344
[31] 0.71511225 −0.35993230 1.29632787 0.13729957 −0.52563320 0.46982761
[37] 0.12234186 −1.23848802 1.29268576 −0.05836899 −0.66205174 −0.07619300
[43] −1.04585532 3.67861858 0.73080674 −1.36358925 −0.78699970 0.41224880
[49] 0.86365984 1.78372714 0.34000000
$x2
[1] −1.008028153 0.753706027 0.339136404 0.394850535 0.822800452
[6] 1.131092940 −0.044501179 −0.247914864 −0.350871896 0.013754292
[11] 0.002728324 0.776690869 −1.002677732 −1.236941825 0.599039509
[16] 0.532717545 0.262159708 −0.373315320 −1.609664791 −2.034626869
[21] 0.563657076 0.440259691 1.690137148 −0.937983631 −1.661222786
[26] 0.325805813 0.111868681 2.189960485 1.200441769 −0.178213068
[31] −0.628382611 −1.777857157 0.893458151 1.009731364 −0.657754484
[36] 0.788648791 −1.343786681 0.993323519 0.021705024 −0.719988792
[41] 0.458443258 −0.624894337 1.466201931 −0.320907500 −1.327935744
[46] 1.397215872 0.352245992 −0.278273447 0.864011297 −0.979787012
[51] 0.370000000

Example2

 Live Demo

List2<−list(y1=rpois(99,10),y2=rpois(99,10))
new<−list(5,3)

Adding new values to List2 −

Example

List2<−mapply(append,List2,new,SIMPLIFY=FALSE)
List2

Output

$y1
[1] 9 19 3 6 10 7 6 8 10 3 6 10 11 7 9 11 13 8 10 8 8 11 10 13 9
[26] 15 5 10 11 10 15 14 5 10 5 7 9 14 10 14 9 11 13 13 12 8 9 13 13 7
[51] 13 9 9 9 13 10 9 13 10 8 9 11 7 8 4 9 11 8 14 8 4 8 11 13 15
[76] 9 8 7 13 10 13 7 13 10 5 8 8 11 7 4 7 15 7 5 11 9 10 13 11 5
$y2
[1] 5 10 8 8 5 14 13 5 7 15 14 12 8 6 15 8 9 6 9 9 14 9 7 9 7
[26] 14 12 2 12 10 14 12 13 11 9 11 10 5 10 9 13 8 8 11 11 18 12 8 14 11
[51] 12 14 18 9 9 16 15 7 13 10 12 8 8 10 7 8 6 14 9 9 10 20 11 10 8
[76] 12 6 9 5 12 10 9 9 6 11 10 11 14 8 11 11 11 9 10 6 9 13 11 13 3

Example3

 Live Demo

List3<−list(z1=runif(49,2,10),z2=runif(49,5,10))
new<−list(3.24542,7.21421)

Adding new values to List3 −

List3<−mapply(append,List3,new,SIMPLIFY=FALSE)
List3

Output

$z1
[1] 7.291533 6.972070 3.586818 6.973179 5.138934 7.952336 3.354811 8.508972
[9] 9.436393 7.226165 4.316177 7.212349 2.944707 8.458374 5.844430 6.623924
[17] 8.705829 2.509108 9.074396 3.360153 9.034577 5.679748 9.096813 6.989252
[25] 3.814996 4.227093 8.546505 7.225875 3.246433 4.620028 7.876439 2.746531
[33] 4.588123 3.770730 7.954941 4.840489 5.309890 3.292286 6.110796 6.506668
[41] 9.662596 5.216663 8.697122 6.700522 3.520535 9.827375 8.321387 4.603970
[49] 5.582278 3.245420
$z2
[1] 7.360781 7.984698 9.110684 9.866965 7.821411 7.912576 8.132087 6.343781
[9] 8.635346 5.778531 9.980152 6.572830 5.289732 7.245998 6.681521 8.756547
[17] 9.282966 5.567102 7.823283 9.973521 7.758861 5.727483 9.618834 5.911291
[25] 7.229435 8.783410 7.815542 7.840888 8.514780 7.798654 7.415919 8.948754
[33] 7.046777 7.855829 6.973687 6.351384 9.041160 9.727344 7.731367 7.100542
[41] 6.987909 7.940805 9.893710 7.400530 9.528001 6.247381 8.108900 8.553423
[49] 9.856233 7.214210

Example4

 Live Demo

List4<−list(a1=sample(0:9,49,replace=TRUE),a2=sample(0:9,49,replace=TRUE))
new<−list(5,2)

Adding new values to List4 −

List4<−mapply(append,List4,new,SIMPLIFY=FALSE)
List4

Output

$a1
[1] 2 4 7 0 8 7 8 8 3 5 9 4 6 6 6 5 4 9 7 1 0 7 8 3 3 6 7 2 3 2 2 5 2 4 7 4 2 0
[39] 7 9 3 3 4 6 7 3 4 0 9 5
$a2
[1] 5 7 4 8 9 4 1 8 5 6 9 0 4 2 7 2 6 2 0 1 6 7 3 9 6 8 2 5 4 1 2 3 7 3 5 4 5 1
[39] 5 7 9 9 3 6 4 4 1 8 4 2