从Python字典中将Unicode值转换为字符串

Question

I've built a python dictionary as follows:

result = {}
for fc in arcpy.ListFeatureClasses():
    for field in arcpy.ListFields(fc):
        result.setdefault(field.name, []).append(fc)

which takes the name of the fields in each table (feature class) and sets tyhem as the key value in the dictionary and goes on to set the name of the table as the value. This works fine because my goal is to find out which tables have the same fields. I can go on to iter over the items and print out the key, value pairs:

for key, value in result.iteritems():
    print key + ": " +  str(value)

which returns:

COMMENTS: [u'TM_FC', u'GT_FC', u'HG_FC', u'PO_FC', u'FU_FC']

I want to print out the key values as a string value instead of the unicode stuff so that it looks like this:

COMMENTS: 'TM_FC', 'GT_FC', 'HG_FC', 'PO_FC', 'FU_FC'

I've been playing around with the 'str' function and various other ways to format and convert to string, but I'm always returning the same original value list. Can anyone suggest a way to accomplish what I'm looking for?

Thanks, Mike

Answer 1

The issue in your code is that you are calling str(value), where value is an array. So what happens is that the array object's __str__ function is getting invoked and it has its own way of making a string representation of the underlying values. This default representation uses repr to show individual elements' values. Since in this case the array elements are unicode string, you see the 'u' in the output.

As a solution, what you want to do is to "unroll" the array manually and build up your own list representation. Here's one way of doing it:

for key, value in result.iteritems():
    print key + ": " +  ",".join(["'%s'" % v for v in value])

Answer 2

I believe this is what you're after

for key, value in result.iteritems():
    print key + ": " +  str([ str(v) for v in value ])

Answer 3

result = {u'Comments':[u'TM_FC', u'GT_FC', u'HG_FC', u'PO_FC', u'FU_FC']}
for k,v in result.iteritems():
    print u'%s:%s' % (k,map(unicode.encode,v))

Simplified with string formatting, and map to change each value to a string, using the default encoding.