Adding, Removing, and Modifying List Elements
| Prepend[list,element] | add element at the beginning of list |
| Append[list,element] | add element at the end of list |
| Insert[list,element,i] | insert element at position i in list |
| Insert[list,element,-i] | insert at position i counting from the end of list |
| Riffle[list,element] | interleave element between the entries of list |
| Delete[list,i] | delete the element at position i in list |
| ReplacePart[list,i->new] | replace the element at position i in list with new |
| ReplacePart[list,{i,j}->new] | replace  with new |
Functions for manipulating elements in explicit lists.
This gives a list with
prepended.
| Out[1]= |  |
This inserts
so that it becomes element number 2.
| Out[2]= |  |
This interleaves
between the entries of the list.
| Out[3]= |  |
This replaces the third element in the list with
.
| Out[4]= |  |
This replaces the 1, 2 element in a 2×2 matrix.
| Out[5]= |  |
Functions like ReplacePart take explicit lists and give you new lists. Sometimes, however, you may want to modify a list "in place", without explicitly generating a new list.
| v={e1,e2,...} | assign a variable to be a list |
| v[[i]]=new | assign a new value to the i element |
Resetting list elements.
This defines
to be a list.
| Out[6]= |  |
This sets the third element to be
.
| Out[7]= |  |
Now
has been changed.
| Out[8]= |  |
| m[[i,j]]=new | replace the   element of a matrix |
| m[[i]]=new | replace the i row |
| m[[All,i]]=new | replace the i column |
Resetting pieces of matrices.
This defines
to be a matrix.
| Out[9]= |  |
This sets the first column of the matrix.
| Out[10]= |  |
This sets every element in the first column to be
.
| Out[11]= |  |
