python - For Loop questions -

i'm used seeing for loops in format:

for number in l: sum = sum + number

i browsing forums , came across piece of code:

count_chars = ".arpz" string = "phillip s. doing job." counts = tuple(string.count(d) for(d)  in count_chars)  print counts 

i'm not sure if for loop, decided rewrite in way understood:

tuple( for(d) in count_chars:     string.count(d)) 

needless say, failed lol. can explain going on, , explain folly of logic? thanks!!

it's not quite for loop such, generator expression. return iterator each element amount of time every character in count_chars occurs in d. adds of these elements tuple.

it (roughly) equivalent to:

counts = [] d in count_chars:     counts.append(string.count(d)) counts = tuple(counts)