editing the table in pandas PYTHON

Question

I need copy the value "a" lower and next I would like that the value of "b" will be also copied lower so many times until it encounters another value etc until the end of column 1

I tried to iterate through the rows and add conditions, unfortunately I wasn’t get the result as I want.
My dataframe looks like:

col1	col2	col3
a
	x1	x2
b
	y1	y2
	p1	p2
c
	q1	q2
…	…	…

Result as I want:

col1	col2	col3
a
a	x1	x2
b
b	y1	y2
b	p1	p2
c
c	q1	q2
…	…	…

Asked By: Przemek

||

Source

Answer 1

Use pandas.fillna with method=ffill:

When used on a column, this replaces the NaN values in a given row with non-NAN values preceding the row.

import pandas as pd 

data = pd.DataFrame({"col1": [1, None, 2, None, None, 3, None, 4, 5, None, None]})

data["col1"] = data["col1"].fillna(method="ffill")

print(data)

Output:

OR

Use pandas.ffill which works similar to above solution and looks more clean. Both the methods mentioned so far allows in place replacement of values.

Using ffill method: df['col1'].ffill(inplace=True).

Answered By: medium-dimensional

editing the table in pandas PYTHON

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