2

I'd like to know how to concatenate part of a string and sort it.

For example, i have a FIELD1 (string) and i should have the numbers of the string separated with ';' in the FIELD2. Only the numbers are repeated in the records. Moreover, i should sort the numbers ascending about their values.

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How do I create an array string, in the field calculator of QGIS, to do this?

2

You need to create a new custom python expression in the Field Calculator to extract the numbers and sort them the way you want.

You can use the following expression:

from qgis.core import *
from qgis.gui import *

@qgsfunction(args='auto', group='Custom')
def extract_digits(text_field, feature, parent):
    split_text = text_field.split()
    num = [int(text) for text in split_text if text.isdigit()]
    num_sort = sorted(num)
    join_sort = ';'.join(['{}'.format (i,) for i in num_sort])
    return join_sort

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Then call the function from the custom expression, and use the field name that contains the street names:

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Do not forget to select the new field in which the sorted digits will be saved.

The output will be like this:

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Update

Based on your comment, I updated the script to take into consideration a semicolon (;) that comes directly after a number. Please use the following code:

from qgis.core import *
from qgis.gui import *

@qgsfunction(args='auto', group='Custom')
def extract_digits(text_field, feature, parent):
    split_text = text_field.split(';')
    merge_text = ' '.join(split_text)
    split_text = merge_text.split()
    num = [int(text) for text in split_text if text.isdigit()]
    num_sort = sorted(num)
    join_sort = ';'.join(['{}'.format (i,) for i in num_sort])
    return join_sort
| improve this answer | |
  • Thank you very much! I'll try, i'm sure that it will works. If i already have the "FIELD2" with random numbers separated with ';' , how can i sort these, with ascending values, in a new field? Should i use array_sort? thanks.. – Mark Jul 18 at 11:12
  • @Mark in your case use the above code to create custom expression. Then check Update existing field and select FIELD2, from the custom expression select extract_digits(“FIELD1”). The numbers will be sorted in ascending order by the code. – ahmadhanb Jul 18 at 11:45
  • ahmadhanb the script doesn't work if there is the number before the ';' (for example ...;avenue 105;...). It doesn't return the number 105 in the list. Is it possible? – Mark Jul 25 at 13:01
  • @Mark Please use the updated code. – ahmadhanb Jul 27 at 0:40
  • Ok, Thank you very much!! – Mark Jul 31 at 11:10

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