Question

The following code is intended to dump a long list of numbers from a csv into stat_by_symbol[symbol] so that I can call the list of numbers using each symbol as a key. For some reason, the code only seems to work for the first symbol. Can someone help me fix the code to work as intended? Many thanks.

with open('zzdata.csv', 'rb') as f:
    reader = csv.reader(f)
    reader.next()
    for symbol in symbols:#symbols in a list
        stat = []
        for row in reader:
            if symbol in row:
                stat.append(row[8])#stat becomes long list of numbers
        stat_by_symbol[symbol] = [stat]

Answer 1

The problem is that you can iterate over reader just once (therefore just the first symbol match).

Try this:

stat_by_symbol = {}
with open('zzdata.csv', 'rb') as f:
    reader = csv.reader(f)
    reader.next()
    for row in reader:
        for symbol in symbols:#symbols in a list
            if symbol in row:
                stat_by_symbol.setdefault(symbol, []).append(row[8])