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3 votes
1 answer
240 views

Test whether an expression contains a particular pattern

How to test whether an expression contains a particular pattern ? I made a function for myself that tests whether an expression contains Plus or not. ...
imida k's user avatar
  • 4,355
1 vote
3 answers
138 views

Why do atomic objects like 56 have a head if they're supposed to be, well, atomic?

This question follows from this one I made earlier. If you ask for FullForm[4] you will get back 4, and that's fine. ...
MadEmperorYuri's user avatar
6 votes
5 answers
375 views

First evaluate in place all subexpressions matching pattern before substituting result

ReplaceAll[expr, {patt1:>rhs1, patt2:>rhs2, …}] works by looking for and making all possible replacements of subexpressions in ...
QuantumDot's user avatar
  • 19.8k
1 vote
1 answer
55 views

Low level built-in function to transpose expression (not array) [closed]

I have an expression like this F[G[1, b], G[3, y], G[4, y], G[5, u]] that I would like to Transpose to obtain ...
QuantumDot's user avatar
  • 19.8k
32 votes
2 answers
2k views

List of atomic expressions

I was surprised to see Graph objects are atomic. Is there a way (through documentation or programmatically) to find all atomic heads? The ones I know of are: ...
Greg Hurst's user avatar
  • 36.8k