How do I make a matrix from a list of vectors in R

Question

Goal  from a list of vectors of equal length  create a matrix where each vector becomes a row   Example    gt  a  lt - list    gt  for  i in 1 10  a  i    lt - c i 1 5   gt  a   1    1  1 1 2 3 4 5    2    1  2 1 2 3 4 5    3    1  3 1 2 3 4 5    4    1  4 1 2 3 4 5    5    1  5 1 2 3 4 5    6    1  6 1 2 3 4 5    7    1  7 1 2 3 4 5    8    1  8 1 2 3 4 5    9    1  9 1 2 3 4 5    10    1  10  1  2  3  4  5   I want           1    2    3    4    5    6    1      1    1    2    3    4    5   2      2    1    2    3    4    5   3      3    1    2    3    4    5   4      4    1    2    3    4    5   5      5    1    2    3    4    5   6      6    1    2    3    4    5   7      7    1    2    3    4    5   8      8    1    2    3    4    5   9      9    1    2    3    4    5  10     10    1    2    3    4    5

User · Answer

gt  library plyr   gt  as matrix ldply a         V1 V2 V3 V4 V5 V6   1    1  1  2  3  4  5   2    2  1  2  3  4  5   3    3  1  2  3  4  5   4    4  1  2  3  4  5   5    5  1  2  3  4  5   6    6  1  2  3  4  5   7    7  1  2  3  4  5   8    8  1  2  3  4  5   9    9  1  2  3  4  5  10   10  1  2  3  4  5

User · Answer

The built-in matrix function has the nice option to enter data byrow  Combine that with an unlist on your source list will give you a matrix  We also need to specify the number of rows so it can break up the unlisted data  That is    gt  matrix unlist a   byrow TRUE  nrow length a            1    2    3    4    5    6    1      1    1    2    3    4    5   2      2    1    2    3    4    5   3      3    1    2    3    4    5   4      4    1    2    3    4    5   5      5    1    2    3    4    5   6      6    1    2    3    4    5   7      7    1    2    3    4    5   8      8    1    2    3    4    5   9      9    1    2    3    4    5  10     10    1    2    3    4    5

User · Answer

One option is to use do call        gt  do call rbind  a          1    2    3    4    5    6    1      1    1    2    3    4    5   2      2    1    2    3    4    5   3      3    1    2    3    4    5   4      4    1    2    3    4    5   5      5    1    2    3    4    5   6      6    1    2    3    4    5   7      7    1    2    3    4    5   8      8    1    2    3    4    5   9      9    1    2    3    4    5  10     10    1    2    3    4    5

User · Answer

simplify2array is a base function that is fairly intuitive  However  since R s default is to fill in data by columns first  you will need to transpose the output   sapply uses simplify2array  as documented in help sapply      gt  t simplify2array a           1    2    3    4    5    6    1      1    1    2    3    4    5   2      2    1    2    3    4    5   3      3    1    2    3    4    5   4      4    1    2    3    4    5   5      5    1    2    3    4    5   6      6    1    2    3    4    5   7      7    1    2    3    4    5   8      8    1    2    3    4    5   9      9    1    2    3    4    5  10     10    1    2    3    4    5

User · Answer

t sapply a       1 max sapply a  length       where  a  is a list   Would work for unequal row size

User · Answer

Not straightforward  but it works    gt  t sapply a  unlist           1    2    3    4    5    6    1      1    1    2    3    4    5   2      2    1    2    3    4    5   3      3    1    2    3    4    5   4      4    1    2    3    4    5   5      5    1    2    3    4    5   6      6    1    2    3    4    5   7      7    1    2    3    4    5   8      8    1    2    3    4    5   9      9    1    2    3    4    5  10     10    1    2    3    4    5

[r] How do I make a matrix from a list of vectors in R?

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