Reading data from csv file put into dictionary python

Question

Blockquote

Help me to read my csv file. I have a csv file test8.csv and I want to read data from that file and put to dict, From the csv file : 1st row is matrices size of value dict that i will create, 2nd row is key of dict and the next is matrix of value of key :

File csv:

1,5 
OFFENSE INVOLVING CHILDREN 
95   
96
35
80
100
2,2
BATTERY,THEFT
173,209   
173,224

Output expectation:

dict={['OFFENSE INVOLVING CHILDREN']: 
      [(95,), (96,), (35,), (80,), (100,)], 
      ['BATTERY', 'THEFT']:[(173, 209), (173, 224)]}

This is my piece of code, and I don't have idea to continue:

_dir = r'D:\s2\semester 3\tesis\phyton\hasil'
with open(os.path.join(_dir, 'test8.csv'), 'rb') as csv_file:
dataReader= csv.reader(csv_file, delimiter=' ', quotechar='|')

You can not have a list as a dictionary key or I'm missing something here. — chanux
– chanux, Commented Jan 16, 2016 at 3:16

tdelaney · Accepted Answer · 2016-01-16 17:22:13Z

4

That isn't a csv file and the csv module can't help you. In a csv file, each line has an equal number of columnar fields separated by a known character such as a comma. you will need to write your own parser for this data.

This script will build up the dictionary (except it uses a tuple for the key because a list won't work...)

# todo: write a testfile so the example works
open("testfile.txt", "w"). write("""1,5 # matriks size
OFFENSE INVOLVING CHILDREN # key for dictionary
95  # list of value 
96
35
80
100
2,2
BATTERY,THEFT
173,209   # list of tuple value
173,224""")

def strip_comment(line):
    return line.split('#', 1)[0].rstrip()

mydict = {}

with open("testfile.txt") as testfile:
    for line in testfile:
        # first line is the next record "matrix size"
        columns, rows = (int(x) for x in strip_comment(line).split(','))
        # next line is the header for this record
        key = tuple(strip_comment(next(testfile)).split(','))
        # the next lines are the rows for this record
        vals = [tuple(int(x) for x in   strip_comment(next(testfile)).split(','))
            for _ in range(rows)]
        mydict[key] = vals

print(mydict)

edited Jan 16, 2016 at 17:22

answered Jan 16, 2016 at 3:15

tdelaney

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4 Comments

Erna Piantari Over a year ago

Acctualy this case is inverse from my question before

Erna Piantari Over a year ago

Sorry... comment is not part of csv file. I write it just for give explanation of my csv example. by the way, using your way... how to read data from file. what is type of testfile ? and what is type of input for testfile. In my case I just have csv file. :)

tdelaney Over a year ago

StringIO is just an object that looks like a file without actually writing a file. I updated the example to remove StringIO but to write the test file and read it from disk.

Erna Piantari Over a year ago

Thank you :) I will use you solution

Wang Zong'an · Accepted Answer · 2016-01-16 04:28:57Z

CSV file is the abbreviation for comma-separated values file. Just treat what you have now as a text file.

You can first read the file into memory:

with open('test8.csv','r') as f:
    lines = f.readlines()

Then, since the structure of the file is known, the lines can be dealt with one by one.

def remove_line_comment(line,comment_char='#'):
    i = 0
    for c in line:
        if c != comment_char:
            i+=1
        else:
            break
    return line[:i]

output = dict() 

for line_number,line in enumerate(lines):
    line = remove_line_comment(line)
    line = line.strip()    # remove empty space on both sides
    line = line.split(',') # split the line with comma as the separator 

    # as indicated, I assume the first line in the file is always 
    # the indicative of the size of key and the size of value of the first diction item 
    if line_number == 0: 
        key_size, value_size = int(line[0]), int(line[1]) 
        line_number_counter = line_number 

    elif line_number == line_number_counter+1:
        # dictionary key cannot be unhashable object 
        key = line[0] if key_size == 1 else tuple(line) 
        value = []

    elif line_number >= line_number_counter+2 and line_number < line_number_counter+1+value_size: 
        value.extend[line]

    elif line_number == line_number_counter+1+value_size:
        value.extend(line)
        output[key] = value

    else:
        key_size, value_size = int(line[0]), int(line[1]) 
        line_number_counter = line_number

This will do the trick.

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