pandas efficient dataframe set row

Question

First I have the following empty DataFrame preallocated:

df=DataFrame(columns=range(10000),index=range(1000))

Then I want to update the d

Answer 1

df=DataFrame(columns=range(10),index=range(10))
a = np.array( [9,9,9,9,9,9,9,9,9,9] )

Update row:

df.loc[2] = a

Using Jeff's idea...

df2 = DataFrame(data=np.random.randn(10,10), index=arange(10))
df2.head().T

I have written up a notebook answering the question: https://www.wakari.io/sharing/bundle/hrojas/pandas%20efficient%20dataframe%20set%20row