Concatenating strings in Python

Question

How can I properly concatenate a variable inside an string in Python?

I am trying to pass service in "Database Connections\\'service'.sde" and (r"C:\GIS\Maps\'.+service+.'.mxd")

service ="Electric"
sde = "Database Connections\\'service'.sde"
mxd = arcpy.mapping.MapDocument(r"C:\GIS\Maps\'.+service+.'.mxd")

so the output looks like

sde = "Database Connections\\Electric.sde"
mxd = arcpy.mapping.MapDocument(r"C:\GIS\Maps\Electric.mxd")

If your question was sufficiently answered, you can accept the most helpful answer. — halfer, Jul 15 '19 at 10:48

cs95 · Answer 1 · 2017-09-07T20:54:57.823

3

I think a better way to do this is using os.path.join:

import os
mxd = arcpy.mapping.MapDocument(os.path.join(*"C:\\GIS\\Maps\\".split('\\') 
                                                    + ["{}.mxd".format(service)]))

Also, note that your back-slashes need to be escaped.

edited Sep 07 '17 at 20:54

answered Sep 07 '17 at 20:43

cs95

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Aren't you mixing methods? Shouldn't you join each component, e.g. `os.path.join(*"C:\\GIS\\Maps\\".split('\\') + ["{}.mxd".format(service)]` Surely the `\\\` is specific to the operating system, and the point of os.path.join is to join making it OS agnostic. – Alexander Sep 07 '17 at 20:53

DjaouadNM · Answer 2 · 2017-09-07T20:50:11.547

1

This is how Python's string concatenation works:

sde = "Database Connections\\" + service + ".sde"
mxd = arcpy.mapping.MapDocument("C:\\GIS\\Maps\\" + service + ".mxd")

edited Sep 07 '17 at 20:50

answered Sep 07 '17 at 20:40

DjaouadNM

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Thanks Mr Geek but I am getting error on second line! – Mona Coder Sep 07 '17 at 20:42
@MonaCoder You should escape the `\` and remove the `r`, check the updated answer. – DjaouadNM Sep 07 '17 at 20:50

score 1 · Answer 3 · answered Sep 07 '17 at 20:59

1

An alternative which bypasses the issue of raw strings can't end with a single backslash:

r'C:\GIS\Maps\%s.mxd' % service

and

r'C:\GIS\Maps\{}.mxd'.format(service)

both work fine, dodging the issue with the string ending in a backslash.

answered Sep 07 '17 at 20:59

TemporalWolf

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Concatenating strings in Python

3 Answers3