Replacing '+' with ', ' for labels in QGIS?

Question

I want to replace a '+' with ', ' to label an attribute looking like "ZT10+ZT20+ZT30" to get "ZT10, ZT20, ZT30" using

regexp_replace("zone_nr", '+', ', ')

but I get an Eval Error: Invalid regular expression '+': quantifier does not follow a repeatable item.

Have you tried replace("zone_nr", '+', ', ')? – Taras Oct 22 '18 at 09:15 — Taras, Oct 22 '18 at 09:15
is using regexp_replace() mandatory? – Jochen Schwarze Oct 22 '18 at 11:43 — Jochen Schwarze, Oct 22 '18 at 11:43

Ian Turton · Accepted Answer · 2018-10-22T09:57:08.717

10

A + is a special symbol to the QGis regular expression engine (it means 1 or more of the preceding character), so you need to escape it by putting a \ in front of it. So you need:

regexp_replace("zone_nr", '\\+', ', ')

edited Oct 22 '18 at 09:57

answered Oct 22 '18 at 09:11

Ian Turton

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Backslash characters must be double escaped \\ – Oto Kaláb Oct 22 '18 at 09:26
but only if I want a \ not if using it as an escape – Ian Turton Oct 22 '18 at 09:34
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@IanTurton actually, no, you need to double escape all backslashes, e.g. '\\\\' would match one backslash. this covers more. or did this change in QGIS 3.x? – geozelot Oct 22 '18 at 09:52
You are right, I'm in java mode just now! – Ian Turton Oct 22 '18 at 09:57

score 9 · Answer 2 · answered Oct 22 '18 at 09:15

9

Or, simply use

replace("zone_nr", '+', ', ')

as this doesn't expect a regexp term (it simply matches all occurences of the specified input string).

answered Oct 22 '18 at 09:15

geozelot

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Oto Kaláb · Answer 3 · 2018-10-22T14:00:58.143

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You can input regular expression to find every single + like [+]

regexp_replace("zone_nr", '[+]', ', ')

edited Oct 22 '18 at 14:00

answered Oct 22 '18 at 09:21

Oto Kaláb

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btw., this will replace the whole string with ', ' if a '+' was found in it! – geozelot Oct 22 '18 at 10:37
You're right I improved my answer – Oto Kaláb Oct 22 '18 at 13:59

Replacing '+' with ', ' for labels in QGIS?

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