How to read several rows from a csv

Question

I have a csv file which contains among other things the names and the phone numbers. I'm only interested in a name only if I've its phone number.

with open(phone_numbers) as f:
    reader = csv.DictReader(f)
    names =  [record['Name'] for record in reader if record['phone']]

But I also want the respective phone number, I've try this:

user_data = {}
with open(phone_numbers) as f:
    reader = csv.DictReader(f)
    user_data['Name'] =  [record['Name'] for record in reader if record['phone']]
    user_data['phone'] = [record['phone'] for record in reader if record['phone']]

But for the second item I got an empty string, I'm guessing that record is a generator and that's why I can iterate over it twice.

I've try to use tuples, but only had worked this way:

user_data = {}
with open(phone_numbers) as f:
    reader = csv.DictReader(f)
    user_data['Name'] =  [(record['Name'],record['phone']) for record in reader if record['phone']]

In that case I have the two variables, phone and Name stored in user_data['Name'], that isn't what I want.

And if I try this:

user_data = {}
with open(phone_numbers) as f:
    reader = csv.DictReader(f)
    user_data['Name'],user_data['phone'] =  [(record['Name'],record['phone']) for record in reader if record['phone']]

I got the following error:

ValueError: too many values to unpack

Edit:

This is a sample of the table:

+--------+---------------+
| Phone | Number |
+--------+---------------+
| Luis | 000 111 22222 |
+--------+---------------+
| Paul | 000 222 3333 |
+--------+---------------+
| Andrea | |
+--------+---------------+
| Jorge | 111 222 3333 |
+--------+---------------+

So all rows have a Name but not all have phones.

Answer 1

Your guess is quite right. If this is the approach you want take - iteration twice, you should use seek(0)

reader = csv.DictReader(f)
user_data['Name'] =  [record['Name'] for record in reader if record['phone']]
f.seek(0)   # role back to begin of file ...
reader = csv.DictReader(f)
user_data['phone'] = [record['phone'] for record in reader if record['phone']]

However, this is not very efficient and you should try and get your data in one roll. The following should do it in one roll:

user_data = {}

def extract_user(user_data, record):
    if record['phone']:
        name = record.pop('name')
        user_data.update({name: record})

[extract_user(user_data, record) for record in reader]

Example:

In [20]: cat phones.csv
name,phone
hans,01768209213
grettel,
henzel,123457123

In [21]: f = open('phones.csv')

In [22]: reader = csv.DictReader(f)

In [24]: %paste
user_data = {}

def extract_user(user_data, record):
    if record['phone']:
        name = record.pop('name')
        user_data.update({name: record})

[extract_user(user_data, record) for record in reader]

## -- End pasted text --
Out[24]: [None, None, None]

In [25]: user_data
Out[25]: {'hans': {'phone': '01768209213'}, 'henzel': {'phone': '123457123'}}

Answer 2

I think there is a much easier approach Because it is a csv file since there are column headings as you indicate then there is a value for phone in each row, it is either nothing or something - so this tests for nothing and if not nothing adds the name and phone to user_data

import csv
user_data = []
with open(f,'rb') as fh:
   my_reader = csv.DictReader(fh)
   for row in my_reader:
       if row['phone'] != ''
           user_details = dict()
           user_details['Name'] = row['Name']
           user_details['phone'] = row['phone']
           user_data.append(user_details)

By using DictReader we are letting the magic happen so we don't have to worry about seek etc.

If I did not understand and you want a dictionary then easy enough

import csv
user_data = dict()
with open(f,'rb') as fh:
   my_reader = csv.DictReader(fh)
   for row in my_reader:
       if row['phone'] != ''
           user_data['Name'] = row['phone']

Answer 3

Is it possible that what you're looking for is throwing away some info in your data file?

In [26]: !cat data00.csv
Name,Phone,Address
goofey,,ade
mickey,1212,heaven
tip,3231,earth

In [27]: f = open('data00.csv')

In [28]: r = csv.DictReader(f)

In [29]: lod = [{'Name':rec['Name'], 'Phone':rec['Phone']} for rec in r if rec['Phone']]

In [30]: lod
Out[30]: [{'Name': 'mickey', 'Phone': '1212'}, {'Name': 'tip', 'Phone': '3231'}]

In [31]: 

On the other hand, should your file contain ONLY Name and Phone columns, it's just

In [31]: lod = [rec for rec in r if rec['Phone']]

Answer 4

You can use dict to convert your list of tuple into dictionary. Also you need to use get if you have record without phone value.

import csv

user_data = {}
with open(phone_numbers) as f:
    reader = csv.DictReader(f)
    user_data = dict([(record['Name'], record['phone']) for record in reader if record.get('phone').strip())

If you want a list of names and phones separately you can use the * expression

with open(phone_numbers) as f:
    reader = csv.DictReader(f)
    names, phones = zip(*[(record['name'], record['value']) for record in reader if record.get('phone').strip()])

Answer 5

I normally use row indexing:

input = open('mycsv.csv', 'r')
user_data = {}

for row in csv.reader(input):
    if row[<row # containing phone>]:
        name = row[<row # containing name>]
        user_data[name] = row[<row # containing phone>]

Answer 6

You were correct the whole time, except for the unpacking.

result = [(record["name"], record["phone"]) for record in reader if record["phone"]]
# this gives [(name1, phone1), (name2,phone2),....]

You have to do [dostuff for name, phone in result] not name,phone = result, which does not make sense semantically and syntactically.