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PadLeft

PadLeft[list, n]
makes a list of length n by padding list with zeros on the left.
PadLeft[list, n, x]
pads by repeating the element x.
PadLeft[list, n, {x1, x2, ...}]
pads by cyclically repeating the elements xi.
PadLeft[list, n, padding, m]
leaves a margin of m elements of padding on the right.
PadLeft[list, {n1, n2, ...}]
makes a nested list with length ni at level i.
PadLeft[list]
pads a ragged array list with zeros to make it full.
  • PadLeft[list, n, ...] always returns a list of length n, except in some special cases where padding is {}.
  • With padding {x1, x2, ..., xs} cyclic repetitions of the xi are effectively laid down and then the list is superimposed on top of them, with the last element of the list lying on an occurrence of xs.  »
  • PadLeft[list, n, padding, -m] truncates the last m elements of list.
  • A margin of Round[(n-Length[list])/2] effectively centers list.
  • PadLeft[list, n, list] effectively treats list as cyclic.
  • PadLeft[list, n, {xlist}] can be used to repeat an individual element that is itself a list.
  • PadLeft[{}, n, {x1, x2, ...}] repeats the sequence of xi as many times as fits in a list of length n.
  • PadLeft[list, {n1, n2, ...}] creates a full array with dimensions {n1, n2, ...} even if list is ragged.  »
  • Negative ni specify to pad on the right.
  • PadLeft[list, {n1, n2}, {{x11, x12, ...}, {x21, ...}, ...}] pads by repeating the block of xij.
  • PadLeft[list, {n1, n2, ...}, list] effectively treats list as cyclic in every dimension.
  • PadLeft[list, {n1, n2, ...}, padding, {m1, m2, ...}] uses margin mi at level i.
  • The object list need not have head List.
EXAMPLESCLOSE ALL
Basic Examples   (6)
Pad with 0 to make the list be of length 10:
Pad with x:
Pad by repeating {x, y, z}:
Leave margin 2 on the right:
Pad to make a 3x5 array:
Pad to make a full array:
Pad with 0 to make the list be of length 10:
In[1]:=
Click for copyable input
Out[1]=
 
Pad with x:
In[1]:=
Click for copyable input
Out[1]=
 
Pad by repeating {x, y, z}:
In[1]:=
Click for copyable input
Out[1]=
 
Leave margin 2 on the right:
In[1]:=
Click for copyable input
Out[1]=
 
Pad to make a 3x5 array:
In[1]:=
Click for copyable input
Out[1]//TableForm=
 
Pad to make a full array:
In[1]:=
Click for copyable input
Out[1]//TableForm=
Scope   (3)
Negative length specifications pad on the right:
Lay down repetitions of the padding, then superimpose the original array:
Use different margins for rows and columns:
Generalizations & Extensions   (1)
Use a head other than List:
Applications   (3)
Put a 1 at the center of a list of 0s:
Pad digit lists to be the same length:
Lay out an array of tiles:
Properties & Relations   (1)
PadLeft[list, n] and PadRight[list, n] pad to make a list of length n:
ArrayPad[list, n] pads with n additional elements on each side:
Possible Issues   (1)
Pad with an element that is itself a list:
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