CODEWITHSUNDEEP
python-3.xpandas
iretex
iretex

Reputation: 69

reading data from a dataframe row by row

I need help with a function that accepts no input and returns a list representing the next row of data extracted from a dataframe

I have tried some iterators but this approach requires me to have an input parameter

def get_next_data_as_list():
    out = list(data.iloc[i])
    i= i + 1
    return out

get_next_data_as_list()

Example output: [1619.5, 1620.0, 1621.0, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, 1.0, 10.0,
     24.0, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, nan, 1615.0, 1614.0, 1613.0, 1612.0, 1611.0, 1610.0,
     1607.0, 1606.0, 1605.0, 1604.0, 1603.0, 1602.0, 1601.5, 1601.0, 1600.0, 7.0, 10.0, 1.0, 10.0, 20.0, 3.0, 20.0,
     27.0, 11.0, 14.0, 35.0, 10.0, 1.0, 10.0, 13.0]

Upvotes: 1

Views: 102

Answers (2)

iretex
iretex

Reputation: 69

Thanks so much, MichaelD. I realized that the generator resets when the function is re-called. I actually was able to fix it by creating an init function which returns the generator and assigns it to a variable; 

```
def get_next_data_as_list_init():
    for i in range(len(data)):
        yield list(data.iloc[i])

x = get_next_data_as_list_init()
```

and then the main function; 

```
def get_next_data_as_list():
    return x.__next__()
```

which only calls the next batch. Thank you very much MichaelD!

Upvotes: 1

MichaelD
MichaelD

Reputation: 1326

One way to do this is to treat your function as a generator:

In [42]: df = pd.DataFrame({'x1':np.random.randn(5), 'x2':np.random.randn(5)})

In [43]: df
Out[43]:
         x1        x2
0  0.891725  0.653889
1  2.260866 -1.521131
2  0.453874  1.416261
3 -0.821557  0.586106
4  1.042644  0.556396

In [44]: def get_next_data_as_list():
    ...:     for i in range(len(df)):
    ...:         yield list(df.iloc[i])
    ...:

In [45]: for x in get_next_data_as_list():
    ...:     print(x)
    ...:
[0.8917247724868814, 0.6538894234684837]
[2.2608656845849993, -1.521131045383185]
[0.4538742078414329, 1.416260697660083]
[-0.8215569227294447, 0.5861059443795276]
[1.0426436741732399, 0.5563956233997533]

To be more explicit:

In [46]: x = get_next_data_as_list()
In [47]: x.__next__()
Out[47]: [0.8917247724868814, 0.6538894234684837]

In [48]: x.__next__()
Out[49]: [2.2608656845849993, -1.521131045383185]

Upvotes: 0

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