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Data is adjacent to headers in csv

how can I put my first row of data in the csv under the header and not in the same row as header?
This is the results.
And down here is my coding.
import os
# ...
filename = 'C:/Desktop/GPS_Trial/Trial6/' + str(d1) + '_' + str(file_counter) +'.csv'
#check whether the file exist or not
rows_to_be_written = []
if not os.path.exists(filename):
rows_to_be_written.append(header1)
rows_to_be_written.append(header2)
rows_to_be_written.append(header3)
rows_to_be_written.append(gps)
rows_to_be_written.append(gps2)
rows_to_be_written.append(gps3)
#write the data into csv
with open(filename, 'a', newline='', encoding='UTF8') as f:
writer = csv.writer(f, delimiter=',')
writer.writerow(rows_to_be_written)
print(gps, gps2, gps3)

You write header with values in one row if it file not exists.
You should write it separately
rows_to_be_written = []
header = None
if not os.path.exists(filename):
header = [header1, header2, header3]
rows_to_be_written.append(gps)
rows_to_be_written.append(gps2)
rows_to_be_written.append(gps3)
# write the data into csv
with open(filename, 'a', newline='', encoding='UTF8') as f:
writer = csv.writer(f, delimiter=',')
if header:
writer.writerow(header)
writer.writerow(rows_to_be_written)
print(gps, gps2, gps3)
Also may be you tried write rows, but you write only one row with header in it. Then change code like this
rows_to_be_written = []
if not os.path.exists(filename):
rows_to_be_written.append([header1, header2, header3])
rows_to_be_written.append([gps, gps2, gps3])
# write the data into csv
with open(filename, 'a', newline='', encoding='UTF8') as f:
writer = csv.writer(f, delimiter=',')
for row in rows_to_be_written:
writer.writerow(row)
print(gps, gps2, gps3)

You need to add the headings separately, and only if they are not there already:
# check whether the file exist or not
if not os.path.exists(filename):
headings = [header1, header2, header3]
else:
headings = None
rows_to_be_written = [gps, gps2, gps3]
# write the data into csv
with open(filename, 'a', newline='', encoding='UTF8') as f:
writer = csv.writer(f)
# Write headings if exist
if headings != None:
writer.writerow(headings)
# Write rows
writer.writerow(rows_to_be_written)
print(gps, gps2, gps3)
I suggest you consider this approach
# Open file to see if there are headings
with open(filename, "r") as f:
try:
has_headings = csv.Sniffer().has_header(f.read(1024))
except csv.Error:
# The file seems to be empty
has_headings = False
# Open to write. In append mode ("a")
with open(filename, "a") as f:
writer = csv.writer(f)
if has_headings:
# Write the rows at the top
writer.writerow(headings_list)
# Use writerows if youe have a 2D list, else use a for loop of writer.writerow
writer.writerows(lists_of_rows)

read and save a specific column from csv file

need help! using previous topics, I found how I can read data form csv file and I do not have problem with this but I can not save a specific column (e.g. column 4 from file.csv) as new.csv file. my script prints column 4 correctly but it does not save it.
import csv
with open('file.csv') as csvfile:
file1 = csv.reader(csvfile, delimiter=',')
fourth_col = []
for cols in file1:
fourth_col = cols[3]
print (fourth_col)
new_file = open('new.csv', 'w')
writer = csv.writer(new_file)
writer.writerows(fourth_col)
new_file.close()

I tried the following code and it is working fine
import csv
new_file = open('new.csv', 'w')
writer = csv.writer(new_file)
with open('file.csv') as csvfile:
file1 = csv.reader(csvfile, delimiter=',')
fourth_col = []
for cols in file1:
fourth_col = cols[3]
print(fourth_col)
writer.writerows(fourth_col)
new_file.flush()
new_file.close()
sample files:
file.csv
a,b,c,d,e
f,g,h,i,j
k,l,m,,n
,,,o,
new.csv
d
i
o

Python file matching and appending

This is one file result.csv:
M11251TH1230
M11543TH4292
M11435TDS144
This is another file sample.csv:
M11435TDS144,STB#1,Router#1
M11543TH4292,STB#2,Router#1
M11509TD9937,STB#3,Router#1
M11543TH4258,STB#4,Router#1
Can I write a Python program to compare both the files and if line in result.csv matches with the first word in the line in sample.csv, then append 1 else append 0 at every line in sample.csv?

import pandas as pd
d1 = pd.read_csv("1.csv",names=["Type"])
d2 = pd.read_csv("2.csv",names=["Type","Col2","Col3"])
d2["Index"] = 0
for x in d1["Type"] :
d2["Index"][d2["Type"] == x] = 1
d2.to_csv("3.csv",header=False)
Considering "1.csv" and "2.csv" are your csv input files and "3.csv" is the result you needed

The solution using csv.reader and csv.writer (csv module):
import csv
newLines = []
# change the file path to the actual one
with open('./data/result.csv', newline='\n') as csvfile:
data = csv.reader(csvfile)
items = [''.join(line) for line in data]
with open('./data/sample.csv', newline='\n') as csvfile:
data = list(csv.reader(csvfile))
for line in data:
line.append(1 if line[0] in items else 0)
newLines.append(line)
with open('./data/sample.csv', 'w', newline='\n') as csvfile:
writer = csv.writer(csvfile)
writer.writerows(newLines)
The sample.csv contents:
M11435TDS144,STB#1,Router#1,1
M11543TH4292,STB#2,Router#1,1
M11509TD9937,STB#3,Router#1,0
M11543TH4258,STB#4,Router#1,0

With only one column, I wonder why you made it as a result.csv. If it is not going to have any more columns, a simple file read operation would suffice. Along with converting the data from result.csv to dictionary will help in quick run as well.
result_file = "result.csv"
sample_file = "sample.csv"
with open(result_file) as fp:
result_data = fp.read()
result_dict = dict.fromkeys(result_data.split("\n"))
"""
You can change the above logic, in case you have very few fields on csv like this:
result_data = fp.readlines()
result_dict = {}
for result in result_data:
key, other_field = result.split(",", 1)
result_dict[key] = other_field.strip()
"""
#Since sample.csv is a real csv, using csv reader and writer
with open(sample_file, "rb") as fp:
sample_data = csv.reader(fp)
output_data = []
for data in sample_data:
output_data.append("%s,%d" % (data, data[0] in result_dict))
with open(sample_file, "wb") as fp:
data_writer = csv.writer(fp)
data_writer.writerows(output_data)

The following snippet of code will work for you
import csv
with open('result.csv', 'rb') as f:
reader = csv.reader(f)
result_list = []
for row in reader:
result_list.extend(row)
with open('sample.csv', 'rb') as f:
reader = csv.reader(f)
sample_list = []
for row in reader:
if row[0] in result_list:
sample_list.append(row + [1])
else:
sample_list.append(row + [0]
with open('sample.csv', 'wb') as f:
writer = csv.writer(f)
writer.writerows(sample_list)

python write to new column in csv file

I want to add a new column to an existing file. But it gets a little complicated with the additional loops i add.
input file:
testfile.csv
col1,col2,col3
1,2,3
3,4,5
4,6,7
output i want:
USA_testfile.csv
col1,col2,col3,country
1,2,3,USA
3,4,5,USA
4,6,7,USA
UK_testfile.csv
col1,col2,col3,country
1,2,3,UK
3,4,5,UK
4,6,7,UK
This is what i have tried:
import csv
import sys
country_list= ['USA', 'UK']
def add_col(csv_file):
for country in country_list:
with open(csv_file, 'rb') as fin:
with open(country+"_timeline_outfile_"+csv_file, 'wb') as fout:
writer = csv.writer(fout, lineterminator='\n')
reader = csv.reader(fin)
all_rows =[]
row = next(reader)
row.append('country')
all_rows.append(row)
print all_rows
for row in reader:
row.append(country)
all_rows.append(row)
writer.writerows(all_rows)
add_col(sys.argv[1])
And this is the error i got:
File "write_to_csv.py", line 33, in add_col
writer.writerows(all_rows)
ValueError: I/O operation on closed file
I was trying to follow this post here

import csv
countries = ['USA', 'UK']
data = list(csv.reader(open('testfile.csv', 'rb')))
for country in countries:
with open('{0}_testfile.csv'.format(country), 'wb') as f:
writer = csv.writer(f)
for i, row in enumerate(data):
if i == 0:
row = row + ['country']
else:
row = row + [country]
writer.writerow(row)

I couldn't reproduce your error, but i cleaned your code a bit.
There is no reason to reopen the input file for every language.
def add_col(csv_file):
with open(csv_file, 'rb') as fin:
reader = csv.reader(fin)
for country in country_list:
fin.seek(0) # jump to begin of file again
with open(country+"_timeline_outfile_"+csv_file, 'wb') as fout:
writer = csv.writer(fout, lineterminator='\n')
header = next(reader)
header.append('country')
writer.writerow(header)
for row in reader:
row.append(country)
writer.writerow(row)

Attempting to merge three columns in CSV, updating original CSV

Some example data:
title1|title2|title3|title4|merge
test|data|here|and
test|data|343|AND
",3|data|343|and
My attempt at coding this:
import csv
import StringIO
storedoutput = StringIO.StringIO()
fields = ('title1', 'title2', 'title3', 'title4', 'merge')
with open('file.csv', 'rb') as input_csv:
reader = csv.DictReader(input_csv, fields, delimiter='|')
for counter, row in enumerate(reader):
counter += 1
#print row
if counter != 1:
for field in fields:
if field == "merge":
row['merge'] = ("%s%s%s" % (row["title1"], row["title3"], row["title4"]))
print row
storedoutput.writelines(','.join(map(str, row)) + '\n')
contents = storedoutput.getvalue()
storedoutput.close()
print "".join(contents)
with open('file.csv', 'rb') as input_csv:
input_csv = input_csv.read().strip()
output_csv = []
output_csv.append(contents.strip())
if "".join(output_csv) != input_csv:
with open('file.csv', 'wb') as new_csv:
new_csv.write("".join(output_csv))
Output should be
title1|title2|title3|title4|merge
test|data|here|and|testhereand
test|data|343|AND|test343AND
",3|data|343|and|",3343and
For your reference upon running this code the first print it prints the rows as I would hope then to appear in the output csv. However the second print prints the title row x times where x is the number of rows.
Any input or corrections or working code would be appreciated.

I think we can make this a lot simpler. Dealing with the rogue " was a bit of a nuisance, I admit, because you have to work hard to tell Python you don't want to worry about it.
import csv
with open('file.csv', 'rb') as input_csv, open("new_file.csv", "wb") as output_csv:
reader = csv.DictReader(input_csv, delimiter='|', quoting=csv.QUOTE_NONE)
writer = csv.DictWriter(output_csv, reader.fieldnames, delimiter="|",quoting=csv.QUOTE_NONE, quotechar=None)
merge_cols = "title1", "title3", "title4"
writer.writeheader()
for row in reader:
row["merge"] = ''.join(row[col] for col in merge_cols)
writer.writerow(row)
produces
$ cat new_file.csv
title1|title2|title3|title4|merge
test|data|here|and|testhereand
test|data|343|AND|test343AND
",3|data|343|and|",3343and
Note that even though you wanted the original file updated, I refused. Why? It's a bad idea, because then you can destroy your data while working on it.
How can I be so sure? Because that's exactly what I did when I first ran your code, and I know better. ;^)

That double quote in the last line is definitely messing up the csv.DictReader().
This works:
new_lines = []
with open('file.csv', 'rb') as f:
# skip the first line
new_lines.append(f.next().strip())
for line in f:
# the newline and split the fields
line = line.strip().split('|')
# exctract the field data you want
title1, title3, title4 = line[0], line[2], line[3]
# turn the field data into a string and append in to the rest
line.append(''.join([title1, title3, title4]))
# save the new line for later
new_lines.append('|'.join(line))
with open('file.csv', 'w') as f:
# make one long string and write it to the new file
f.write('\n'.join(new_lines))

import csv
import StringIO
stored_output = StringIO.StringIO()
with open('file.csv', 'rb') as input_csv:
reader = csv.DictReader(input_csv, delimiter='|', quoting=csv.QUOTE_NONE)
writer = csv.DictWriter(stored_output, reader.fieldnames, delimiter="|",quoting=csv.QUOTE_NONE, quotechar=None)
merge_cols = "title1", "title3", "title4"
writer.writeheader()
for row in reader:
row["merge"] = ''.join(row[col] for col in merge_cols)
writer.writerow(row)
contents = stored_output.getvalue()
stored_output.close()
print contents
with open('file.csv', 'rb') as input_csv:
input_csv = input_csv.read().strip()
if input_csv != contents.strip():
with open('file.csv', 'wb') as new_csv:
new_csv.write("".join(contents))