How to use ReplaceAll on an expression that contains a rule

Question

I know I have seen this before but can't seem to locate it today.

I am trying to take an expression that has some rules in it and replace one of that parts that contain a rule using ReplaceAll

For a simple example consider:

testExpression = {"stuff", Axes -> {False, True}}
(* {"stuff", Axes -> {False, True}} *)

and I want to replace the

Axes -> {False, True}

with

Axes -> False

I have tried

testExpression /. 
 Hold[Axes -> {False, True}] -> Hold[Axes -> False]
(* {"stuff", Axes -> {False, True}} *)

as well as

testExpression /. 
 Hold[Rule[Axes , {False, True}]] -> Hold[Rule[Axes , False]]
(* {"stuff", Axes -> {False, True}} *)

I promise to add this to my set of notes if someone could kindly enlighten me.

Carl Woll · Accepted Answer · 2019-03-31 16:31:02Z

8

Here are a couple possibilities:

testExpression /. Rule[Axes, {False, True}] -> Axes -> False
testExpression /. HoldPattern[Axes -> {False, True}] -> Axes -> False

{"stuff", Axes -> False}

{"stuff", Axes -> False}

answered Mar 31 '19 at 16:31

Carl Woll

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mikado · Accepted Answer · 2019-03-31 22:03:20Z

6

I think this is just a matter of getting the parentheses right

testExpression /. (Axes -> {False, True}) -> (Axes -> False)
(* {"stuff", Axes -> False} *)

answered Mar 31 '19 at 22:03

mikado

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$\begingroup$ I'd have posted this too. (+1) $\endgroup$ – J. M. will be back soon♦ Mar 31 '19 at 22:21
$\begingroup$ Wish I could accept them both $\endgroup$ – Jack LaVigne Apr 1 '19 at 14:29

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2 Answers 2