Plot specific rows of a pandas dataframe

use iloc to slice your df:

data.iloc[499:999].plot(y='value')

this will slice from row 500 up to but not including row 1000

Example:

In [35]:
df = pd.DataFrame(np.random.randn(10,2), columns=list('ab'))
df.iloc[2:6]

Out[35]:
          a         b
2  0.672884  0.202798
3  0.514998  1.744821
4 -1.982109 -0.770861
5  1.364567  0.341882

df.iloc[2:6].plot(y='b')