The goal here is to see how many unique values i have in my database. This is the code i have written:
apps = pd.read_csv('ConcatOwned1_900.csv', sep='\t', usecols=['appid'])
apps[('appid')] = apps[('appid')].astype(int)
apps_list=apps['appid'].unique()
b = apps.groupby('appid').size()
blist = b.unique()
print len(apps_list), len(blist), len(set(b))
>>>7672 2164 2164
Why is there difference in those two methods?
Due to request i am posting some of my data:
Unnamed: 0 StudID No appid work work2
0 0 76561193665298433 0 10 nan 0
1 1 76561193665298433 1 20 nan 0
2 2 76561193665298433 2 30 nan 0
3 3 76561193665298433 3 40 nan 0
4 4 76561193665298433 4 50 nan 0
5 5 76561193665298433 5 60 nan 0
6 6 76561193665298433 6 70 nan 0
7 7 76561193665298433 7 80 nan 0
8 8 76561193665298433 8 100 nan 0
9 9 76561193665298433 9 130 nan 0
10 10 76561193665298433 10 220 nan 0
11 11 76561193665298433 11 240 nan 0
12 12 76561193665298433 12 280 nan 0
13 13 76561193665298433 13 300 nan 0
14 14 76561193665298433 14 320 nan 0
15 15 76561193665298433 15 340 nan 0
16 16 76561193665298433 16 360 nan 0
17 17 76561193665298433 17 380 nan 0
18 18 76561193665298433 18 400 nan 0
19 19 76561193665298433 19 420 nan 0
20 20 76561193665298433 20 500 nan 0
21 21 76561193665298433 21 550 nan 0
22 22 76561193665298433 22 620 6.0 3064
33 33 76561193665298434 0 10 nan 837
34 34 76561193665298434 1 20 nan 27
35 35 76561193665298434 2 30 nan 9
36 36 76561193665298434 3 40 nan 5
37 37 76561193665298434 4 50 nan 2
38 38 76561193665298434 5 60 nan 0
39 39 76561193665298434 6 70 nan 403
40 40 76561193665298434 7 130 nan 0
41 41 76561193665298434 8 80 nan 6
42 42 76561193665298434 9 100 nan 10
43 43 76561193665298434 10 220 nan 14
IIUC based on attached piece of the dataframe it seems that you should analyze b.index, not values of b. Just look:
b = apps.groupby('appid').size()
In [24]: b
Out[24]:
appid
10 2
20 2
30 2
40 2
50 2
60 2
70 2
80 2
100 2
130 2
220 2
240 1
280 1
300 1
320 1
340 1
360 1
380 1
400 1
420 1
500 1
550 1
620 1
dtype: int64
In [25]: set(b)
Out[25]: {1, 2}
But if you do it for b.index you'll get the same values for all 3 methods:
blist = b.index.unique()
In [30]: len(apps_list), len(blist), len(set(b.index))
Out[30]: (23, 23, 23)