Map - Remove All Where Key Matches Pattern

Developers Coding Questions
#1

Anyone removed entries from a map, e.g. one built from a json string, using a pattern / condition on the key value?

I've read the JSON below into a map and can't seem to get the removeAll function to work like some online examples explain for Groovy. I want to remove all the "image" entries or all the "background" entries. Any tips?

{
"background01": "http://www.bom.gov.au/products/radar_transparencies/IDR043.background.png",
"background02": "http://www.bom.gov.au/products/radar_transparencies/IDR043.locations.png",
"image1": "http://www.bom.gov.au/radar/IDR043.T.202110292344.png",
"image2": "http://www.bom.gov.au/radar/IDR043.T.202110292349.png",
"image3": "http://www.bom.gov.au/radar/IDR043.T.202110292354.png",
"image4": "http://www.bom.gov.au/radar/IDR043.T.202110292359.png",
"image5": "http://www.bom.gov.au/radar/IDR043.T.202110300004.png",
"image6": "http://www.bom.gov.au/radar/IDR043.T.202110300009.png",
"image7": "http://www.bom.gov.au/radar/IDR043.T.202110300014.png"
}
#2

The second example here may help: groovy removeAll closure not removing elements in list - Stack Overflow

Your closure logic could check:

it.key against some subString matching and/or fixed list of values, depending on whether you know ahead of time what entries you might be looking for.

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#3

Hmmm... Still a little unsure what you mean, if I want to remove all entries from the Map with a prefix of "image" or a prefix of "background" as the key value, any tips on how to apply the stack overflow example?

Probably worth emphasising this is a map and not a list... Am guessing you / they mean to get the keyset to use in the function...

And thanks for responding btw, sounds a little demanding in my initial response...

#4

Ah, it looks like Map's removeAll was only added in Groovy 2.5, and Hubitat seems to be on 2.4.x.

You could try brute forcing it something like this. Someone else may have a more elegant idea:

def input =
        [
        background01: "http://www.bom.gov.au/products/radar_transparencies/IDR043.background.png",
        background02: "http://www.bom.gov.au/products/radar_transparencies/IDR043.locations.png",
        image1: "http://www.bom.gov.au/radar/IDR043.T.202110292344.png",
        image2: "http://www.bom.gov.au/radar/IDR043.T.202110292349.png",
        image3: "http://www.bom.gov.au/radar/IDR043.T.202110292354.png",
        image4: "http://www.bom.gov.au/radar/IDR043.T.202110292359.png",
        image5: "http://www.bom.gov.au/radar/IDR043.T.202110300004.png",
        image6: "http://www.bom.gov.au/radar/IDR043.T.202110300009.png",
        image7: "http://www.bom.gov.au/radar/IDR043.T.202110300014.png"
        ]
    
    def newKeys = []
    input.keySet().each
    {
        if(it.substring(0, 5) != "image")
        {
            newKeys += it
        }
    }
    
    def output = input.subMap(newKeys)
    
    log.debug output
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#5

That's the kind of info I was missing, it's a pain when there's so many instructions available but are not applicable. Thanks @tomw.

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#6

And I think the keySet().each bit is ultimately what I need....

#7

not sure whether "it" is being resolved....

#8

Never had an issue with it being resolved but another option using the iteration method would be

if(!it.startsWith("image"))
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#9

That's what I tried (I thought), but maybe I need to sleep on it and try it with more night time hours behind me....

1 Like
#10

What about

def output = input.findAll {!it.key.startsWith("image")}

Though this of course doesn't remove anything from input. Does that matter for you?
(Removing is also possible, but too annoying to type on a phone :wink: )

2 Likes
#11

That's what I would have thought would work.... Can only hope my attention to detail is not what it should be, and I will correct this during more more appropriate hours later this morning....

#12

I'm thinking I may need to adjust my approach to just get something working, like you point out...

#13

(Fwiw, if you want to remove items from the map you are iterating over, that's a bit of a problem (untill remove all is introduced). So you'll have to resort to cloning up front or so. )

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#14

The one I posted worked when I tested it. I would do what @thebearmay posted in place of the substring part in my demo, since his is more intuitive (and therefore less error prone).

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#15

Back home. Just to ("probably" unnecessarily :wink: ) elaborate. Here is a version that removes the items from the original Map instance. (it works as findAll returns a new Map instance)

class TestSnippets extends GroovyTestCase {
    void testMapRemove() {
        def input =
                [
                        background01: "http://www.bom.gov.au/products/radar_transparencies/IDR043.background.png",
                        background02: "http://www.bom.gov.au/products/radar_transparencies/IDR043.locations.png",
                        image1      : "http://www.bom.gov.au/radar/IDR043.T.202110292344.png",
                        image2      : "http://www.bom.gov.au/radar/IDR043.T.202110292349.png",
                        image3      : "http://www.bom.gov.au/radar/IDR043.T.202110292354.png",
                        image4      : "http://www.bom.gov.au/radar/IDR043.T.202110292359.png",
                        image5      : "http://www.bom.gov.au/radar/IDR043.T.202110300004.png",
                        image6      : "http://www.bom.gov.au/radar/IDR043.T.202110300009.png",
                        image7      : "http://www.bom.gov.au/radar/IDR043.T.202110300014.png"
                ]
        input.findAll { !(it.key =~ "^image.*") } each { input.remove it.key }
        //input.retainAll {it.key =~"^image.*"} for later groovy
        assert input.size() == 7
    }
}
3 Likes
#16

Not that the other options don't work, but was able to get the findAll setup working from @jasper 's last post, thanks for that.

EDIT: Also funny that I now look back at the scraping of the shtml file I use as the source of the radar image links.... using a little known function over a map... called findAll().... :blush:

Simon

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