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Python csv string to array

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How do I convert a CSV file to an array in Python?

Line 1: We import the NumPy library. Line 3-4: We open the sampleCSV file and we pass both CSVData and the delimiter to NumPy np. genfromtxt () function, which returns the data into a 2D array. Line 6: We finally print the result which shows that now our CSV data converted into a 2D array.

How do you convert a string to an array in Python?

split() method to convert string to array in Python. Python's split() method splits the string using a specified delimiter and returns it as a list item. The delimiter can be passed as an argument to the split() method. If we don't give any delimiter, the default will be taken as whitespace.

How will you read CSV data into an array in NumPy?

To read CSV data into a record in a Numpy array you can use the Numpy library genfromtxt() function, In this function's parameter, you need to set the delimiter to a comma. The genfromtxt() function is used quite frequently to load data from text files in Python.


You can convert a string to a file object using io.StringIO and then pass that to the csv module:

from io import StringIO
import csv

scsv = """text,with,Polish,non-Latin,letters
1,2,3,4,5,6
a,b,c,d,e,f
gęś,zółty,wąż,idzie,wąską,dróżką,
"""

f = StringIO(scsv)
reader = csv.reader(f, delimiter=',')
for row in reader:
    print('\t'.join(row))

simpler version with split() on newlines:

reader = csv.reader(scsv.split('\n'), delimiter=',')
for row in reader:
    print('\t'.join(row))

Or you can simply split() this string into lines using \n as separator, and then split() each line into values, but this way you must be aware of quoting, so using csv module is preferred.

On Python 2 you have to import StringIO as

from StringIO import StringIO

instead.


Simple - the csv module works with lists, too:

>>> a=["1,2,3","4,5,6"]  # or a = "1,2,3\n4,5,6".split('\n')
>>> import csv
>>> x = csv.reader(a)
>>> list(x)
[['1', '2', '3'], ['4', '5', '6']]

The official doc for csv.reader() https://docs.python.org/2/library/csv.html is very helpful, which says

file objects and list objects are both suitable

import csv

text = """1,2,3
a,b,c
d,e,f"""

lines = text.splitlines()
reader = csv.reader(lines, delimiter=',')
for row in reader:
    print('\t'.join(row))

Per the documentation:

And while the module doesn’t directly support parsing strings, it can easily be done:

import csv
for row in csv.reader(['one,two,three']):
    print row

Just turn your string into a single element list.

Importing StringIO seems a bit excessive to me when this example is explicitly in the docs.


As others have already pointed out, Python includes a module to read and write CSV files. It works pretty well as long as the input characters stay within ASCII limits. In case you want to process other encodings, more work is needed.

The Python documentation for the csv module implements an extension of csv.reader, which uses the same interface but can handle other encodings and returns unicode strings. Just copy and paste the code from the documentation. After that, you can process a CSV file like this:

with open("some.csv", "rb") as csvFile: 
    for row in UnicodeReader(csvFile, encoding="iso-8859-15"):
        print row

Not a generic CSV parser but usable for simple strings with commas.

>>> a = "1,2"
>>> a
'1,2'
>>> b = a.split(",")
>>> b
['1', '2']

To parse a CSV file:

f = open(file.csv, "r")
lines = f.read().split("\n") # "\r\n" if needed

for line in lines:
    if line != "": # add other needed checks to skip titles
        cols = line.split(",")
        print cols