Nothing

✖
`Nothing`

✖

Nothing

represents an element of a list that will automatically be removed.

✖

Nothing[…]

gives Nothing.

Details

Nothing is removed as part of the standard evaluation process. It is not removed in expressions that are held or inactive.

Examples

open allclose all

Basic Examples (2)Summary of the most common use cases

Any occurrence of Nothing is automatically removed in a list:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-nl13pg

Out[1]=1

Replace an element of a list with Nothing to remove it:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-5d8jdv

Out[1]=1

Scope (2)Survey of the scope of standard use cases

Nothing is removed wherever it appears in a list:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-gmhxt

Out[1]=1

Nothing is not removed from heads other than List:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-gh2u8v

Out[1]=1

Generalizations & Extensions (1)Generalized and extended use cases

When Nothing appears as a head, it reduces any expression to Nothing:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-llrstb

Out[1]=1

In[2]:=2

✖

https://wolfram.com/xid/0en0wofle-415rbb

Out[2]=2

Applications (1)Sample problems that can be solved with this function

Delete lines from a plot, leaving only isolated points:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-x93o2n

Out[1]=1

In[2]:=2

✖

https://wolfram.com/xid/0en0wofle-oo29l

Out[2]=2

Properties & Relations (3)Properties of the function, and connections to other functions

Nothing is removed during the standard evaluation process:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-bs6g21

Out[1]=1

In[2]:=2

✖

https://wolfram.com/xid/0en0wofle-86mw4x

Out[2]=2

Remove primes from a list by replacing them with Nothing:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-v2jio

Out[1]=1

Delete the primes with a pattern:

In[2]:=2

✖

https://wolfram.com/xid/0en0wofle-nzk1o2

Out[2]=2

Select the non-primes:

In[3]:=3

✖

https://wolfram.com/xid/0en0wofle-dqqeth

Out[3]=3

Nothing will only disappear inside lists:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-r3iems

Out[1]=1

In[2]:=2

✖

https://wolfram.com/xid/0en0wofle-c63hxf

Out[2]=2

An empty Sequence[] will evaporate inside any head except those with special attributes:

In[3]:=3

✖

https://wolfram.com/xid/0en0wofle-rw3umz

Out[3]=3

In[4]:=4

✖

https://wolfram.com/xid/0en0wofle-zthm1n

Out[4]=4

Possible Issues (1)Common pitfalls and unexpected behavior

Nothing is removed as part of standard evaluation, so it is kept in held expressions:

In[1]:=1

✖

https://wolfram.com/xid/0en0wofle-ogtsgt

Out[1]=1

When the Hold is released, Nothing is removed:

In[2]:=2

✖

https://wolfram.com/xid/0en0wofle-i79i9f

Out[2]=2

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