Python - Building a string from a loop

Question

I have a set of points that have latitude and longitude values and I am trying to create a string in the following format in order to work with the Gmaps API:

 LatitudeX,LongitudeX|LatitudeY,LongitudeY

The final string will be built using an unknown number of lat long pairs.

My previous experience is with PHP and, whilst I have managed to get something working however, it seems a bit clumsy and I was wondering if there as a more 'pythonic' way to achieve the result.

Here's what I have so far:

 waypoints = ''

 for point in points:
     waypoints = waypoints+"%s,%s" % (point.latitude, point.longitude)+"|"

 waypoints = waypoints[:-1]

Any advice appreciated.

Thanks

Mark Byers · Accepted Answer · 2011-11-11 20:33:42Z

11

Use str.join:

waypoints = '|'.join("{0},{1}".format(p.latitude, p.longitude) for p in points)

answered Nov 11, 2011 at 20:33

Mark Byers

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2 Comments

user395760 Over a year ago

Also note the use of a generator expression (+1 btw). Never use a list comprehension when a generator expression works.

Colin Dunklau Over a year ago

The join method on strings is one of the fastest ways to concatenate strings. @Dan Check out skymind.com/~ocrow/python_string for examples... and note that the naive concatenation with the + operator has terrible performance compared with str.join.

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