Creating a new pandas dataframe from shape

Question

I have information on total number of rows and number of columns for a new pandas dataframe

import pandas as pd
nRow = 10
nCol = 4

Based on this information I want to create a new dataframe where each element will be filled by 1

Is there any direct method available with pandas to achieve this?

Beside the point, but this smells like an XY problem. What's the end goal? E.g. if your data isn't labeled and is all the same dtype, a NumPy array might be more appropriate, like in Paul's answer without the dataframe wrapping it. — wjandrea
– wjandrea, Commented Oct 22 at 1:56

PaulS · Accepted Answer · 2025-10-21 17:57:55Z

7

Another possible solution, which uses np.ones to create an array of ones with which to create the wanted dataframe:

pd.DataFrame(np.ones((nRow,nCol)))

edited Oct 21 at 17:57

answered Oct 21 at 17:52

PaulS

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wjandrea · Accepted Answer · 2025-10-22 01:59:36Z

5

There is no such method in pandas, but you could create the DataFrame in one line like this

df = pd.DataFrame(1, index=range(nRow), columns=range(nCol))

edited Oct 22 at 1:59

wjandrea

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answered Oct 21 at 21:11

Matias Bertani

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wjandrea · Accepted Answer · 2025-10-22 02:03:37Z

2

I can't think of a direct method in pandas.

You can do something like this.

import numpy as np

# Generate custom but automatic column names
cols = [f"Col{i+1}" for i in range(nCol)]

# Create the DataFrame
df = pd.DataFrame(np.nan, index=range(nRow), columns=cols)

edited Oct 22 at 2:03

wjandrea

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answered Oct 21 at 17:39

Natre

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1 Comment

Matias Bertani Oct 21 at 21:12

This is not full of ones

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