convert csv file to list of dictionaries

Question

I have a csv file

col1, col2, col3
1, 2, 3
4, 5, 6

I want to create a list of dictionary from this csv.

output as :

a= [{'col1':1, 'col2':2, 'col3':3}, {'col1':4, 'col2':5, 'col3':6}]

How can I do this?

score 107 · Accepted Answer · edited Jan 12 '22 at 15:13

107

Use csv.DictReader:

import csv

with open('test.csv') as f:
    a = [{k: int(v) for k, v in row.items()}
        for row in csv.DictReader(f, skipinitialspace=True)]

Will result in :

[{'col2': 2, 'col3': 3, 'col1': 1}, {'col2': 5, 'col3': 6, 'col1': 4}]

edited Jan 12 '22 at 15:13

idjaw

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answered Feb 05 '14 at 08:38

falsetru

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4

For the lazy, from the linked page - `skipinitialspace`: When `True`, whitespace immediately following the delimiter is ignored. – Flash Mar 07 '17 at 12:45
2

@falsetru, Here why the output is not coming in this order? [{'col1':1, 'col2':2, 'col3':3}, {'col1':4, 'col2':5, 'col3':6}] – V-T Dec 08 '17 at 04:22
@V-T, Dictionary in python 3.6- is not an ordered collection. – falsetru Dec 08 '17 at 07:28
3

@V-T, If you use Python 3.6+, OrderedDict which guarantee order: https://docs.python.org/3/library/csv.html#csv.DictReader – falsetru Dec 08 '17 at 07:29
For unicode support on python2.7 you could use `import unicodecsv as csv`. – dimid Oct 28 '19 at 12:24
@falsetru: I see in your [linked docs](https://docs.python.org/3/library/csv.html#csv.DictReader) that as of Python 3.8 the return type is once again `dict`. Is there a way to explicitly enforce an order? – hpy Jun 10 '20 at 22:36
2

@hpy, Since Python 3.7+, insertion order of dict is guaranteed. https://mail.python.org/pipermail/python-dev/2017-December/151283.html => Don't worry, just use DictReader :) – falsetru Jun 10 '20 at 22:41
Whew, that's great to know. Thank you @falsetru! I wonder why that isn't mentioned in the documentation somewhere (or I probably missed it...)... – hpy Jun 11 '20 at 10:18
1

@hpy, It's mentioned in ["What's New In Python 3.7 - Summary - Release Hightlights"](https://docs.python.org/3/whatsnew/3.7.html#summary-release-highlights) > Python data model improvements: > the insertion-order preservation nature of dict objects has been declared to be an official part of the Python language spec. – falsetru Jun 11 '20 at 13:22
1

@hpy, also in [Built-in Types - `dict`](https://docs.python.org/3/library/stdtypes.html#dict) > "Dictionaries preserve insertion order. Note that updating a key does not affect the order. Keys added after deletion are inserted at the end.", "Changed in version 3.7: Dictionary order is guaranteed to be insertion order. This behavior was an implementation detail of CPython from 3.6." – falsetru Jun 11 '20 at 13:23

score 34 · Answer 2 · answered May 18 '18 at 02:07

34

Another simpler answer:

    import csv
    with open("configure_column_mapping_logic.csv", "r") as f:
        reader = csv.DictReader(f)
        a = list(reader)
        print a

answered May 18 '18 at 02:07

Simon

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This turns it into a list of tuples, not dicts? – ndtreviv Apr 26 '21 at 10:42
`print(a)` should be outside of the `with` block because at that time the file is no needed anymore. Additionally: why not `a = list(csv.DictReader(f))`? – pabouk - Ukraine stay strong Oct 25 '21 at 09:41

Ashwini Chaudhary · Answer 3 · 2014-02-05T08:49:50.913

10

Using the csv module and a list comprehension:

import csv
with open('foo.csv') as f:
    reader = csv.reader(f, skipinitialspace=True)
    header = next(reader)
    a = [dict(zip(header, map(int, row))) for row in reader]
print a

Output:

[{'col3': 3, 'col2': 2, 'col1': 1}, {'col3': 6, 'col2': 5, 'col1': 4}]

edited Feb 05 '14 at 08:49

answered Feb 05 '14 at 08:38

Ashwini Chaudhary

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score 2 · Answer 4 · answered May 10 '16 at 23:46

2

# similar solution via namedtuple:    

import csv
from collections import namedtuple

with open('foo.csv') as f:
  fh = csv.reader(open(f, "rU"), delimiter=',', dialect=csv.excel_tab)
  headers = fh.next()
  Row = namedtuple('Row', headers)
  list_of_dicts = [Row._make(i)._asdict() for i in fh]

answered May 10 '16 at 23:46

MOCKBA

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Only answer getting with same order of CSV – V-T Dec 08 '17 at 05:00

Prasanth Bendra · Answer 5 · 2022-04-22T11:31:11.517

2

Answering here after long time as I don't see any updated/relevant answers.

df = pd.read_csv('Your csv file path')  
data = df.to_dict('records')
print( data )

edited Apr 22 '22 at 11:31

answered Mar 27 '22 at 07:26

Prasanth Bendra

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score 1 · Answer 6 · answered Feb 05 '14 at 08:55

Well, while other people were out doing it the smart way, I implemented it naively. I suppose my approach has the benefit of not needing any external modules, although it will probably fail with weird configurations of values. Here it is just for reference:

a = []
with open("csv.txt") as myfile:
    firstline = True
    for line in myfile:
        if firstline:
            mykeys = "".join(line.split()).split(',')
            firstline = False
        else:
            values = "".join(line.split()).split(',')
            a.append({mykeys[n]:values[n] for n in range(0,len(mykeys))})

score 1 · Answer 7 · edited Dec 04 '18 at 19:25

1

Simple method to parse CSV into list of dictionaries

with open('/home/mitul/Desktop/OPENEBS/test.csv', 'rb') as infile:
  header = infile.readline().split(",")
  for line in infile:
    fields = line.split(",")
    entry = {}
    for i,value in enumerate(fields):
      entry[header[i].strip()] = value.strip()
      data.append(entry)

edited Dec 04 '18 at 19:25

Brian H.

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answered Oct 27 '17 at 07:42

Mitul Panchal

496
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convert csv file to list of dictionaries

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