Accessing Headers

CHAT data files record metadata such as the participants’ demographic information in a header section, which has lines starting with the @ character and is typically found at the top of a data file. The following is the header section of Brown/Eve/010600a.cha from CHILDES:

@UTF8
@PID:       11312/c-00034743-1
@Begin
@Languages: eng
@Participants:      CHI Target_Child , MOT Mother , COL Investigator , RIC Investigator
@ID:        eng|Brown|CHI|1;06.00|female|||Target_Child|||
@ID:        eng|Brown|MOT||female|||Mother|||
@ID:        eng|Brown|COL|||||Investigator|||
@ID:        eng|Brown|RIC|||||Investigator|||
@Date:      15-OCT-1962
@Time Duration:     10:00-11:00
@Types:     long , toyplay , TD

CHAT has the following methods to access the commonly needed information from the headers:

Let’s use Eve’s data to see these methods in action.

import rustling
path = "path/to/your/local/Brown.zip"
eve = rustling.read_chat(path, filter_files="Eve")

Ages

ages() returns the age information of the participant "CHI" – typically, only the age of the target child is available.

ages() understands CHAT’s age format that looks like 1;06.00 (= one year, six months, and zero days old) and wraps it in a helper class Age:

eve.ages()
# [Age('1;06.00'),
#  Age('1;06.00'),
#  Age('1;07.00'),
#  Age('1;07.00'),
#  Age('1;08.00'),
#  Age('1;09.00'),
#  Age('1;09.00'),
#  Age('1;09.00'),
#  Age('1;10.00'),
#  Age('1;10.00'),
#  Age('1;11.00'),
#  Age('1;11.00'),
#  Age('2;00.00'),
#  Age('2;00.00'),
#  Age('2;01.00'),
#  Age('2;01.00'),
#  Age('2;02.00'),
#  Age('2;02.00'),
#  Age('2;03.00'),
#  Age('2;03.00')]

Age has the method in_months() for converting the age information into months (as floats, useful for downstream data analyses and making plots):

[age.in_months() for age in eve.ages()]
# [18.0,
#  18.0,
#  19.0,
#  19.0,
#  20.0,
#  21.0,
#  21.0,
#  21.0,
#  22.0,
#  22.0,
#  23.0,
#  23.0,
#  24.0,
#  24.0,
#  25.0,
#  25.0,
#  26.0,
#  26.0,
#  27.0,
#  27.0]

Languages

languages() returns the language information. Eve’s data is naturally in English. In datasets with more than one language (bi-/multilingualism), the by_file=True flag would indicate the languages in individual files according to the headers.

eve.languages()
# ['eng']

Participants

participants() returns the participants (e.g., "CHI") in the data. by_file=True is also available if you need the information by individual files.

eve.participants(by_file=True)  # a list of lists of Participant objects
# [[Participant(code='CHI', name='', role='Target_Child'),
#   Participant(code='MOT', name='', role='Mother'),
#   Participant(code='COL', name='', role='Investigator'),
#   Participant(code='RIC', name='', role='Investigator')],
#   ...
#  ]

Each participant has their information available via attributes through the helper class Participant. For instance:

chi = eve.participants(by_file=True)[0][0]
chi
# Participant(code='CHI', name='', role='Target_Child')
chi.age
# Age('1;06.00')
chi.role
# 'Target_Child'

Other Header Information

For any header information not given by one of the implemented methods above, headers() gives a list of headers, where each header is a Headers object for each data file, and you can walk through the object for information you need.

headers = eve.headers()  # a list of Headers objects
headers[0]
# Headers(languages=["eng"], participants=[...4], date=datetime.date(1962, 10, 15))

See the documentation of Headers for more details.