CODEWITHSUNDEEP
pythonlistcsvdictionarywriter
gJg
gJg

Reputation: 147

Writing csv in rows and columns

I am so close to being done but cant get my head around this problem. I am writing to csv and my code keeps giving me this output.

 dict,a,b,c,d
 ,,,,
 list,1,2,3,4

I want it to be as follows:

 dict, list
 a,1
 b,2
 c,3
 d,4

The code is:

    ##Opening my dictionary .cvs file
    with open('some_file.csv', mode='r') as infile:
        reader = csv.reader(infile,)
        DICT = {rows[0]:rows[1] for rows in reader if len(rows) == 2}

    ##Opening my enquiry list .cvs file
    datafile = open(self.filename, 'r')
    datareader = csv.reader(datafile)
    n1 = []
    for row in datareader:
        n1.append(row)

        n = list(itertools.chain(*n1))

    headings = ['dict', 'list']

    ##Writing to .cvs file       
    with open(asksaveasfilename(), 'w') as fp:
        a = csv.writer(fp)
        # write row of header names
        a.writerow(n)

        # build up a list of the values in DICT corresponding to the keys in n
        values = []
        for name in n:
            if name in DICT:
                values.append(DICT[name])
            else:
                values.append("Not Available")

        # now write them out
        a.writerow(values)

I tried using writerows but this prints the data wrong also

d,i,c,t
a
b
c
d
l,i,s,t
1
2
3
4

SOLUTION:

    for nameValueTuple in zip(n,values):
    a.writerow(nameValueTuple)

Did the trick

Upvotes: 1

Views: 387

Answers (2)

brice
brice

Reputation: 25039

Writing the data directly

import csv

DICT = {a:a*a for a in [1,2,3,4,5]}
n = [2, 5, 99, 3]

headings = ['dict', 'list']

##Writing to .cvs file       
with open("try.csv", 'w') as fp:
  a = csv.writer(fp)
  a.writerow(headings)
  for name in n:
    if name in DICT:
       a.writerow([name, DICT[name]])
    else:
       a.writerow([name, "Not Available"])

This will result in try.csv containing:

dict,list
2,4
5,25
99,Not Available
3,9

Doing the processing first, then writing the processed rows:

You can also do the processing and write everything at once:

import csv

DICT = {a:a*a for a in [1,2,3,4,5,6]}
ns = [2,3,99,5]

headings = ['dict', 'list']

ns_squared = [DICT[name] if name in DICT else "NOT_FOUND" for name in names]

print(ns_squared) #=> [4, 9, 'NOT_FOUND', 25]

rows = zip(ns,ns_squared)

with open("try.csv", 'w') as fp:
  a = csv.writer(fp)
  a.writerow(headings)
  a.writerows(rows)

This will then result in:

dict,list
2,4
3,9
99,NOT_FOUND
5,25

Using zip to turn columns into row

If you have columns as lists, you can turn these into rows by using the zip() builtin function. For example:

>>> column1 = ["value", 1, 2, 3, 4]
>>> column2 = ["square", 2, 4, 9, 16]
>>> zip(column1,column2)
[('value', 'square'), (1, 2), (2, 4), (3, 9), (4, 16)]

Upvotes: 1

WattoWatto
WattoWatto

Reputation: 159

Its been long time since I done python, (I'm assuming variable 'values' is an array)

I think your writerow should be something like;

#not sure about the syntax, mate...
a.writerow([for x in values])

otherwise use bultiin function zip

Hope this helps...

Upvotes: 0

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