Python, for loop

Question

I have the following code:

def get_asset_info(asset_list):

    import datetime

    today = datetime.datetime.today()
    day = today.strftime("%d")

    for i in range( len( asset_list )):
        raw_info = get_OHLC( asset_list[i], 15, get_server_time() )

        info = raw_info['result'][asset_list[i]]
        head = "time,open,high,low,close,vwap,volume,count"

        formatted_info = ""

        for i in range(len(info[0])):
            formatted_info = formatted_info + info[0][i] + ","

        file = open(asset_list[i]+"_"+day, "a")
        file.write(head + "\n")
        file.write(formatted_info)
        file.close()

It is supposed to get some values, convert it into a string and write it to a file, dynamically generated. It's not working like this and all the values are put in the same file.

If I change the last part of the code like the following, the files are generated:

    formatted_info = str(info[0][0]) + "," + str(info[0][1]) + "," + str(info[0][2]) + "," + str(info[0][3]) + "," + str(info[0][4]) + "," + str(info[0][5]) + "," + str(info[0][6]) + "," + str(info[0][7])

    file = open(asset_list[i]+"_"+day, "a")
    file.write(head + "\n")
    file.write(formatted_info)
    file.close()

So the problem, as I can see, is in the for loop I create to generate my string, but there's no sense since the code that generates the file is not in the same loop.

Any ideas?

indent your file writing block, otherwise its only writing out the last instance of formatted_info — gold_cy
– gold_cy, Commented Jun 1, 2017 at 10:23
You're using the same variable i for your inner loop and your outer loop. Use a different variable. — khelwood
– khelwood, Commented Jun 1, 2017 at 10:24
It is possible to get rid of the inner loop altogether, just use this: formatted_info = ",".join(info[0]) + "," — Błotosmętek
– Błotosmętek, Commented Jun 1, 2017 at 10:29

freakish · Accepted Answer · 2017-06-01 14:14:40Z

2

for i in range( len( asset_list )):
    ...
    for i in range(len(info[0])):
        ...
    # now what do you think i is now?
    file = open(asset_list[i]+"_"+day, "a")

Changing second i to j should do the trick:

for i in range( len( asset_list )):
    ...
    for j in range(len(info[0])):
        formatted_info = formatted_info + info[0][j] + ","

    file = open(asset_list[i]+"_"+day, "a")

or even better:

for i in range( len( asset_list )):
    ...
    for piece in info[0]:
        formatted_info = formatted_info + str(piece) + ","

    file = open(asset_list[i]+"_"+day, "a")

or finally better:

for i in range( len( asset_list )):
    ...
    formatted_info = ','.join(str(obj) for obj in info[0]) + ','
    file = open(asset_list[i]+"_"+day, "a")

edited Jun 1, 2017 at 14:14

answered Jun 1, 2017 at 10:26

freakish

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3 Comments

Frey Over a year ago

First code is ok, second one must be used like this to work: for piece in info[0]: formatted_info = formatted_info + str(piece) + "," Third one, a disaster. Lots of thank

freakish Over a year ago

@Frey Well, there's no str in your original code which suggests that those arrays contain strings. Anyway I've updated the answer.

Frey Over a year ago

That's an elegant way of doing the thing. Just forgot to modify the code when I copied it

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