How to see if map keys contain certain strings?

Question

Suppose I have a slice of strings like:

fruits := {"apple", "orange", "banana"}

and a map like

box:= map[string]int{
    "chicken": 1,
    "drinks": 4,
    "apples": 42,
}

What is the most efficient way to check whether the box contains any apple, orange or banana? Notice that here we seek not exact match but a key that CONTAINS certain strings. So simple key search does not work here.

I know I can extract keys from the map:

keys := make([]string)
for k := range box {
    keys = append(keys, k)
}

And then iterate over both slices to search among the keys:

for _, f := range fruits {
  for _, k in keys {
      if strings.Contains(k, f) {
       fmt.Println("Fruit found!")
       }
   }

But that refutes the advantage of using map instead of slice for string searchs. So is there better way to do so?

Burak Serdar · Accepted Answer · 2020-01-31 16:18:37Z

5

You don't need to extract the keys:

for _, f := range fruits {
  for k,fruit := range box {
      if strings.Contains(k, f) {
       fmt.Printf("Fruit found!: %s",fruit)
       }
   }
}

If you only need to check if key exists, you can write for k := range box

Since this is a contains search, there is no easy way to do it. If it was a begins with search, there are other data structures you might want to look at, such as a trie, or prefix-tree. There isn't standard library support for those.

answered Jan 31, 2020 at 16:18

Burak Serdar

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