Creating label formatted like " 1,000' " from numeric field?

Using two string functions in the QGIS calculator on version 2.6 Mac OS X I was able to accomplish this. Here are the steps:

1. Using the field calculator create a new field that is a string type with a relevant width.

2. Run the following expression to set the value of the field:
   concat( format_number( "Field_name" , 0) , '\'')

This created a column with a string formatted as I wanted so for example the number 2000 would be formatted to 2,000' with the trailing ' which stands for feet.

QGIS has created a function called format_number to address this. You simply do format_number(12345,0) to get 12,345.

You can do digit grouping easily in Python. Here's a function that I've used, which I think I found on StackOverflow:

def digitgroup(n, sep = ','):
    if n == "": n = 0
    s = str(n)[::-1]
    groups = []
    i = 0
    while i < len(s):
        groups.append(s[i:i+3])
        i += 3
    return sep.join(groups)[::-1]