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Convert a NumPy array into a csv file
  • Last Updated : 02 Sep, 2020

In this article, we are going to see different methods to save an NumPy array into a CSV file. CSV file format is the easiest and useful format for storing data

There are different methods by which we can save the NumPy array into a CSV file

Method 1: Using Dataframe.to_csv().

This method is used to write a Dataframe into a CSV file.

Example: Converting the array into pandas Dataframe and then saving it to CSV format.



Python3




# import necessary libraries
import pandas as pd
import numpy as np
  
# create a dummy array
arr = np.arange(1,11).reshape(2,5)
  
# display the array
print(arr)
  
# convert array into dataframe
DF = pd.DataFrame(arr)
  
# save the dataframe as a csv file
DF.to_csv("data1.csv")

Output:

[[ 1  2  3  4  5]
[ 6  7  8  9 10]]

Method 2: Using numpy_array.tofile().

This method is used to write an array into the file.

Example: Create an array then save into a CSV file.

Python3




# import the necessary library
import numpy as np
  
# create a dummy array
arr = np.arange(1,11)
  
# display the array
print(arr)
  
# use the tofile() method 
# and use ',' as a separator
# as we have to generate a csv file
arr.tofile('data2.csv', sep = ',')

Output:



[ 1  2  3  4  5  6  7  8  9 10]

Method 3: Using numpy.savetext().

This method is used to save an array to a text file.

Example: Create an array then save as a CSV file.

Python3




# import numpy library
import numpy
  
# create an array
a = numpy.array([[1, 6, 4],
                 [2, 4, 8],
                 [3, 9, 1]])
  
# save array into csv file
numpy.savetxt("data3.csv", a, 
              delimiter = ",")

Output:


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