Pandas series between two date time files

Question

My question is about using Pandas time series.

I have one file(Spots) that has pandas time series for a month's data with 7.5 seconds range. Example :

2016-11-01 00:00:00,0

2016-11-01 00:00:07.500000,1

2016-11-01 00:00:15,2

2016-11-01 00:00:22.500000,3

2016-11-01 00:00:30,4

The other file(Target) has just time information .

Example:

2016-11-01 00:00:05

2016-11-01 00:00:07

2016-11-01 00:00:23

2016-11-01 00:00:25

I want to check which spot does the target date time belong to: Output in above example :

2016-11-01 00:00:00,0 '\t' count of targets in this spot = 2

2016-11-01 00:00:07.500000,1 '\t' count of targets in this spot = 0

2016-11-01 00:00:15,2 '\t' count of targets in this spot = 0

2016-11-01 00:00:22.500000,3 '\t' count of targets in this spot = 0

2016-11-01 00:00:30,4 '\t' count of targets in this spot = 2

Thank you so much in advance. Kinda let me know if this is clear otherwise I can try to explain more.

Answer 1

The basic difference between size and count is that size includes NaN values and count does not include any NaN values.

Here is an example to illustrate the difference:

In [46]:

df = pd.DataFrame({'a':[0,0,1,2,2,2], 'b':[1,2,3,4,np.NaN,4], 'c':np.random.randn(6)})

df

Out[46]:

   a   b       c

0  0 1  1.067627

1  0 2  0.554691

2  1 3  0.458084

3  2 4  0.426635

4  2 NaN -2.238091

5  2 4  1.256943

In [48]:

print(df.groupby(['a'])['b'].count())

print(df.groupby(['a'])['b'].size())

a

0    2

1    1

2    2

Name: b, dtype: int64

a

0    2

1    1

2    3

dtype: int64