Question

I have data from travel diaries which has been read in from a csv file. I have it set up as a dictionary with a bunch of lists. E.g.:

print diary['ID'][1] gives 123456789
print diary['TravelReferenceDay'][1] gives 1 for a Monday

I want to randomnly select an ID from the array based on the day e.g.:

random.choice(diary['ID']) if diary['TravelReferenceDay'] == 1

I can arrange the data by TravelReferenceDay in the csv file. I had tried the groupby method to split up the array:

groups = []
uniquekeys = []
for k, g in groupby(diary, diary['TravelReferenceDay']):
    groups.append(list(g))      # Store group iterator as a list
    uniquekeys.append(k)

But that gave the error:

TypeError: 'list' object is not callable

Could you suggest a way to achieve this? Thanks.

Answer 1

My solution with a list comprehensions:

In [1]: import random
   ...: diary = {'ID': ['11', '22', '33', '44', '55'], 'TravelReferenceDay': [1, 1, 2, 3, 1]}
   ...: monday_diary = [x for n, x in enumerate(diary['ID']) if diary['TravelReferenceDay'][n] == 1]

In [2]: monday_diary
Out[2]: ['11', '22', '55']

In [3]: random.choice(monday_diary)
Out[3]: '22'