I need to declare empty dataframe in python in order to append it later in a loop. Below the line of the declaration:
result_table = pd.DataFrame([[], [], [], [], []], columns = ["A", "B", "C", "D", "E"])
It throws an error:
AssertionError: 5 columns passed, passed data had 0 columns
Why is it so? I tried to find out the solution, but I failed.
import pandas as pd
df = pd.DataFrame(columns=['A','B','C','D','E'])
That's it!
Because you actually pass no data. Try this
result_frame = pd.DataFrame(columns=['a', 'b', 'c', 'd', 'e'])
if you then want to add data, use
result_frame.loc[len(result_frame)] = [1, 2, 3, 4, 5]
I think it is better to create a list or tuples or lists and then call DataFrame only once:
L = []
for i in range(3):
#some random data
a = 1
b = i + 2
c = i - b
d = i
e = 10
L.append((a, b, c, d, e))
print (L)
[(1, 2, -2, 0, 10), (1, 3, -2, 1, 10), (1, 4, -2, 2, 10)]
result_table = pd.DataFrame(L, columns = ["A", "B", "C", "D", "E"])
print (result_table)
A B C D E
0 1 2 -2 0 10
1 1 3 -2 1 10
2 1 4 -2 2 10
result_table = pd.DataFrame(columns = ["A", "B", "C", "D", "E"] )