How to read one single line of csv data in Python?

Question

There is a lot of examples of reading csv data using python, like this one:

import csv
with open('some.csv', newline='') as f:
  reader = csv.reader(f)
  for row in reader:
    print(row)

I only want to read one line of data and enter it into various variables. How do I do that? I've looked everywhere for a working example.

My code only retrieves the value for i, and none of the other values

reader = csv.reader(csvfile, delimiter=',', quotechar='"')
for row in reader:
  i = int(row[0])
  a1 = int(row[1])
  b1 = int(row[2])
  c1 = int(row[2])
  x1 = int(row[2])
  y1 = int(row[2])
  z1 = int(row[2])

what is the structure of your csv? What is `row` when you are iterating through reader? — dm03514, Jun 23 '13 at 15:27

Ashwini Chaudhary · Answer 1 · 2016-08-12T08:12:08.047

170

To read only the first row of the csv file use next() on the reader object.

with open('some.csv', newline='') as f:
  reader = csv.reader(f)
  row1 = next(reader)  # gets the first line
  # now do something here 
  # if first row is the header, then you can do one more next() to get the next row:
  # row2 = next(f)

or :

with open('some.csv', newline='') as f:
  reader = csv.reader(f)
  for row in reader:
    # do something here with `row`
    break

edited Aug 12 '16 at 08:12

answered Jun 23 '13 at 15:29

Ashwini Chaudhary

244,495
58
464
504

2

What happens if you want to just read the first line rather than iterating? This approach moves the iterator to the next line and you'll lose the value if you want to iterate over the whole list again later. – Mahsan Nourani Jun 08 '21 at 15:29
3

@MahsanNourani The file pointer can be moved to anywhere in the file, `file.seek(0)` will move it back to the start for example and then you can re-read from start. You'll have to keep the file open obviously to perform seek operation. In general, the point of using iterators is that you'll get one item a time, hence saving memory, if you need multiple iteration on the same data, list is a better datastructure. – Ashwini Chaudhary Jun 09 '21 at 05:23
I was just trying to print the first line of the file before doing anything with the data hence my question! This solution is great, I didn't know that. Thanks :) – Mahsan Nourani Jun 10 '21 at 01:11

dm03514 · Answer 2 · 2019-05-15T11:51:48.310

46

you could get just the first row like:

with open('some.csv', newline='') as f:
  csv_reader = csv.reader(f)
  csv_headings = next(csv_reader)
  first_line = next(csv_reader)

edited May 15 '19 at 11:51

answered Jun 23 '13 at 15:29

dm03514

54,664
18
108
145

2

Probably, it is good to add "with open('csv_file', 'r')" as f: csv_reader = csv.reader(f) ..." – Sanchit May 15 '19 at 10:45

score 30 · Answer 3 · edited Jun 19 '15 at 18:48

30

You can use Pandas library to read the first few lines from the huge dataset.

import pandas as pd

data = pd.read_csv("names.csv", nrows=1)

You can mention the number of lines to be read in the nrows parameter.

edited Jun 19 '15 at 18:48

josliber

43,891
12
98
133

answered Jun 19 '15 at 18:46

Aravind Krishnakumar

2,727
1
28
25

score 19 · Answer 4 · answered Jan 31 '20 at 22:20

Just for reference, a for loop can be used after getting the first row to get the rest of the file:

with open('file.csv', newline='') as f:
    reader = csv.reader(f)
    row1 = next(reader)  # gets the first line
    for row in reader:
        print(row)       # prints rows 2 and onward

score 16 · Answer 5 · edited Apr 07 '16 at 15:08

16

From the Python 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 drop your string data into a singleton list.

edited Apr 07 '16 at 15:08

Luke

1,369
1
13
37

answered Jan 23 '15 at 04:08

Robert Elwell

6,598
1
28
32

score 8 · Answer 6 · answered Sep 22 '16 at 03:07

8

The simple way to get any row in csv file

import csv
csvfile = open('some.csv','rb')
csvFileArray = []
for row in csv.reader(csvfile, delimiter = '.'):
    csvFileArray.append(row)
print(csvFileArray[0])

answered Sep 22 '16 at 03:07

Oscar.Chou

81
1
3

3

To make this work in python3, just remove the 'b' in 'rb' – Enrique Avina Jan 13 '18 at 22:57
1

This just works, actually without the `delimiter='.'`. – suvtfopw Jan 24 '19 at 07:05
1

To answer the posters question, just add a `break` after the `csvFileArray.append(row)` and it will only read the first line. – StratusBase LLC Sep 17 '19 at 02:48

score 6 · Answer 7 · answered Apr 08 '20 at 14:01

6

To print a range of line, in this case from line 4 to 7

import csv

with open('california_housing_test.csv') as csv_file:
    data = csv.reader(csv_file)
    for row in list(data)[4:7]:
        print(row)

answered Apr 08 '20 at 14:01

Biplob Das

2,818
21
13

I only got this to work by using `with open('C:\\Users\\username\\Desktop\\csv_file.csv', encoding='utf-8') as csv_file:` as the first line – jeppoo1 Apr 07 '21 at 08:56

score 1 · Answer 8 · answered Nov 12 '22 at 17:40

I think the simplest way is the best way, and in this case (and in most others) is one without using external libraries (pandas) or modules (csv). So, here is the simple answer.

""" no need to give any mode, keep it simple """
with open('some.csv') as f:
    """ store in a variable to be used later """
    my_line = f.nextline()
    """ do what you like with 'my_line' now """

score -1 · Answer 9 · answered Apr 21 '23 at 16:51

-1

For Python3 use: my_line = next(f)

answered Apr 21 '23 at 16:51

Petr Vokáč

39
5

How to read one single line of csv data in Python?

9 Answers9

Linked

Related