python pandas flatten a dataframe to a list

You can use .flatten() on the DataFrame converted to a NumPy array:

df.to_numpy().flatten()

and you can also add .tolist() if you want the result to be a Python list.

Edit

In previous versions of Pandas, the values attributed was used instead of the .to_numpy() method, as mentioned in the comments below.

Maybe use stack?

df.stack().values
array([1/2/2014, a, 3, z1, 1/3/2014, c, 1, x3], dtype=object)

(Edit: Incidentally, the DF in the Q uses the first row as labels, which is why theyre not in the output here.)

You can try with numpy

import numpy as np
np.reshape(df.values, (1,df.shape[0]*df.shape[1]))