Question

I have a 30 n random sample from a list which I write to a file.

I would rather like to tag the lines that went to the sample by writing in the end “in_sample” or “not_in_sample”.

Now it looks like this:

mysample=random.sample(list, 30)
for i in mysample:
    out.write("%s\n" % (i))

I only write out lines from the sample but I would want the file to look like this:

line 1 in_sample

line 2 not_in_sample

line 3 in_sample

line 4 not_in_sample

The file looked the same before but without the last column.

Am I clear?

Answer 1

One way to do that is to sample on your list indexes instead of on its content.

For example, if your list is called lst:

indexes_samples = sorted(random.sample(range(len(lst)), 30))

for i in indexes_samples:
    lst[i]  # do what you want

Or maybe I think you might want to do something like:

idx = sorted(random.sample(range(len(lst)), 30))

j = 0
for i,num in enumerate(lst):
    if j <= len(idx) and i == idx[j]:
        msg = 'line {} in sample'
        j += 1
    else:
        msg = 'line {} not in sample'

    print(msg.format(num))   # out.write() or whatever