How do I read a 2 column csv file and create a dictionary?

Question

For example given the following csv

ID, type
1 , A
2 , B
3 , C

it should generate a dictionary that looks like this

{'1':A, '2':B, '3':C}

Here's what I have so far, but its's associating the entire column into 1 dictionary

import csv

reader = csv.DictReader(open('TIS_annotation.csv'))
result = {}

for row in reader:
    for column, value in row.iteritems():
        result.setdefault(column, []).append(value)
print result

Do you have repeating ID's? – Padraic Cunningham Oct 24 '16 at 22:20 — Padraic Cunningham, Oct 24 '16 at 22:20
@PadraicCunningham no i dont thankfully haha – ahtmatrix Oct 25 '16 at 03:48 — ahtmatrix, Oct 25 '16 at 03:48

score 10 · Accepted Answer · answered Oct 24 '16 at 21:33

10

When you iterate over each row in reader, the row variable contains all the information you need to make a new entry to the dictionary. You can simply write

for row in reader:
    result[row['ID']] = row[' type']

To make the dictionary you want.

answered Oct 24 '16 at 21:33

Erik Godard

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score 6 · Answer 2 · answered Oct 24 '16 at 22:15

6

It's simpler than you thought:

import csv

with open('TIS_annotation.csv') as f:
    next(f)  # Skip the header
    reader = csv.reader(f, skipinitialspace=True)
    result = dict(reader)
    print result

Output:

{'1 ': 'A', '3 ': 'C', '2 ': 'B'}

Basically, reader yields a series of rows, each has two elements, feed that into dict and you have it made.

answered Oct 24 '16 at 22:15

Hai Vu

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This is absolutely the correct answer. I just worked though something similar [converting to a Counter.](https://stackoverflow.com/q/53642743/25197) – GollyJer Dec 06 '18 at 04:52

n1tk · Answer 3 · 2016-10-24T22:39:29.763

Other way is to create a tuple and convert to dictionary the tuples, will work for even for txt files.

for row in reader:
    ID = row[0] 
    data_type = row[1]
    myTuples.append(tuple([ID, data_type]))

result = dict(myTuples)
print result

resuling:

{'1 ': ' A', '3 ': ' C', '2 ': ' B', 'ID': ' type'}

you can skip header or first row on read the data/csv so 'ID': ' type' will not be in dict.

shortest way skip first row and also append positions of the row without creating ID and type variables:

next(f) #for skipping first row in the file
myTuples = [] #store tuples from col1 and col2
for row in reader:
    myTuples.append(tuple([row[0], row[1]])) #append col1 and col 2 to myTuples

result = dict(myTuples)
print result

resulting:

{'1 ': ' A', '3 ': ' C', '2 ': ' B'}

How do I read a 2 column csv file and create a dictionary?

3 Answers3

Other way is to create a tuple and convert to dictionary the tuples, will work for even for txt files.

resuling:

shortest way skip first row and also append positions of the row without creating ID and type variables:

resulting: