How do I remove a substring/character from a string in Scala?

Question

I am writing a program in which I need to filter a string. So I have a map of characters, and I want the string to filter out all characters that are not in the map. Is there a way for me to do this?

Let's say we have the string and map:

str = "ABCDABCDABCDABCDABCD"

Map('A' -> "A", 'D' -> "D")

Then I want the string to be filtered down to:

str = "BCBCBCBCBC"

Also, if I find a given substring in the string, is there a way I can replace that with a different substring?

So for example, if we have the string:

"The number ten is even"

Could we replace that with:

"The number 10 is even"

What if you had Map('A' -> "B", 'C' -> "D") or maybe even Map('A' -> "W", 'X' -> "D")? How then should str be filtered? — jwvh
– jwvh, Commented Jan 13, 2020 at 11:22
If you only need to have a Set of characters, maybe you should use a Set instead of a Map. — Luis Miguel Mejía Suárez
– Luis Miguel Mejía Suárez, Commented Jan 13, 2020 at 11:46

SCouto · Accepted Answer · 2020-01-13 10:45:19Z

3

To filter the String with the map is just a filter command:

val str = "ABCDABCDABCDABCDABCD"
val m = Map('A' -> "A", 'D' -> "D")

str.filterNot(elem => m.contains(elem))

A more functional alternative as recommended in comments

str.filterNot(m.contains)

Output

scala> str.filterNot(elem => m.contains(elem))
res3: String = BCBCBCBCBC

To replace elements in the String:

string.replace("ten", "10")

Output

scala> val s  = "The number ten is even"
s: String = The number ten is even

scala> s.replace("ten", "10")
res4: String = The number 10 is even

edited Jan 13, 2020 at 10:45

answered Jan 13, 2020 at 10:02

SCouto

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2 Comments

SCouto Over a year ago

Glad to help, please, accept the answer so anyone with the same question can reach to it quickly

Tim Over a year ago

This can be simplified to str.filterNot(m.contains) which is a more functional way of doing it, but perhaps more confusing for a beginner.

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