my question related to this link here
Excellent explanation in the above link. But in my situation is little bit different.
user meetings
178787 287750
178787 151515
178787 158478
576585 896352
576585 985639
576585 456988
expected result is
user meetings
178787 "[287750,151515,158478]"
576585 "[896352,985639,456988]"
How can i make this done using python with above code. Thanks in advance.
You could read in the file, line by line, split the lines and add the meeting to a dictionary where the key is the user. This can be done very neatly using the method seen here.
We can then write this dictionary back to the same file using tabs to make everything line up.
So, assuming your file is called f.csv, the code would look something like:
d = {}
for l in open('f.csv').read().split('\n')[1:-1]:
u, m = l.split()
d.setdefault(u, []).append(m)
with open('f.csv', 'w') as f:
f.write('user\tmeetings\n')
for u, m in d.items():
f.write(u + '\t' + str(m) + '\n')
Which produces the desired output of:
user meetings
178787 ['287750', '151515', '158478']
576585 ['896352', '985639', '456988']
from collections import defaultdict
import csv
inpath = '' # Path to input CSV file
outpath = '' # Path to output CSV file
output = defaultdict(list) # Dictionary like {user_id: [meetings]}
for row in csv.DictReader(open(inpath)):
output[row['user']].append(row['meetings'])
with open(outpath, 'w') as f:
for user, meetings in output.items():
row = user + ',' + str(meetings) + '\n'
f.write(row)
Since user is going to be the key, let's stuff a dictionary. Note: this will ultimately load the entire file into memory once, but it does not require the file to be sorted by user first. Also note the output is not sorted either (because dict.items() does not retrieve dictionary items in any deterministic order).
output = {}
with f as open('input.csv'):
for line in f:
user, meeting = line.strip('\r\n').split()
# we strip newlines before splitting on whitespace
if user not in output and user != 'user':
# the user was not found in the dict (and we want to skip the header)
output[user] = [meeting] # add the user, with the first meeting
else: # user already exists in dict
output[user].append(meeting) # add meeting to user entry
# print output header
print("user meetings") # I used a single space, feel free to use '\t' etc.
# lets retrieve all meetings per user
for user, meetings in output.items() # in python2, use .iteritems() instead
meetings = ','.join(_ for _ in meetings) # format ["1","2","3"] to "1,2,3"
print('{} "[{}]"'.format(user, meetings))
Fancier: sort output. I do this by sorting the keys first. Note that this will use even more memory since I am creating a list of the keys too.
# same as before
output = {}
with f as open('input.csv'):
for line in f:
user, meeting = line.strip('\r\n').split()
# we strip newlines before splitting on whitespace
if user not in output and user != 'user':
# the user was not found in the dict (and we want to skip the header)
output[user] = [meeting] # add the user, with the first meeting
else: # user already exists in dict
output[user].append(meeting) # add meeting to user entry
# print output header
print("user meetings") # I used a single space, feel free to use '\t' etc.
# sort my dict keys before printing them:
for user in sorted(output.keys()):
meetings = ','.join(_ for _ in output[user])
print('{} "[{}]"'.format(user, meetings))
