Splitting string with house number in QGIS Field Calculator

Question

I have a string field with housenumber which contains values like:

housenumber
5
12 a
15 b
18 c

What are the right expressions for the field calculator to write only the number in "field1" and only the string in "field2":

field1	field2
5	NULL
12	a
15	b
18	c

I guess regular expressions. But how to implement it?

Answer 1

Extract information with a regular expression is always a bit tricky without having all the data, and can lead to unexpected results. For example what should happen if the field has data like 'a 22 a'.

Taken that into account and with the sample data that you provide you can try with these two regular expressions.

# For field1
regexp_substr("hausnummer", '[0-9]*')

# For field2
regexp_substr("hausnummer", '[[:alpha:]]+')

BTW there is a wonderful online tool that you can use to test regular expressions for different engines/languages

Answer 2

• Find all consecutive numbers (first occurrences):

  regexp_substr( "hausnummer", '(\\d+)' )
  

• Find all consecutive characters (first occurrences, in range a - z & A - Z):

  regexp_substr( "hausnummer", '([a-zA-Z]+)' )
  

Answer 3

I would use

f1 = left("hausnummer",strpos("hausnummer",' ')-1)

f2 = right("hausnummer",length("hausnummer")-strpos("hausnummer",' '))