Today I was given an excel sheet containing an X and Y column of GPS coordinates that someone in another department had attempted to display in ArcMap. They were successful in that they got some points to display, but these points were located somewhere in the Atlantic, I was asked to 'fix' it.
In these situations more information is always useful, but none was forthcoming, so I made an educated guess. Often when GPS units capture data in British National Grid, they miss out the first number of each X and Y value as these correspond to the map sheet identifying letter and rarely change for the average user. These letters have numerical equivalents, so I tacked on the correct numbers to each coordinate pair and displayed them in Arc. Lo and behold, they were now in the right place.
I decided to knock together a quick Python script to automate this process, which gave me the opportunity to learn how to interface with excel sheets directly (I would usually export to *.csv or *.dbf) using the xlrd module and refresh my memory about the idiosyncrasies of the wonderful pyshp module. Below is the code I wrote in an hour or so. Originally I was going to write a small interface for it and pass it on to the department, but that is a task for another day. It's a bit ugly, but it does what is needed.
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