Develop Reference

How to rewrite only one field (line[n]) in csv but in same time be able to work with data?

I have a csv file with three lines and three columns here.
This is the csv file
At first I want to print all the lines.
Subsequently, for each of them, program check whether it is written in the second field(index 1) USA. If so, program will take the price from the third field and multiply it by two.
Now I need to rewrite this doubled price instead of 2000 (in line with the USA)
import csv
with open('countries.csv', 'r') as source:
reader = csv.reader(source)
writer = csv.writer(source)
for line in reader:
print(*line, sep=';')
with open('countries.csv', 'r') as source:
reader = csv.reader(source)
for line in reader:
if line[2] == "USA":
actual_price = int(line[2])
print(actual_price)
new_price = int(actual_price) * 2
print(new_price)
Someone has already advised me to use the creation of a new file.
But this causes problems when I want to work with the data in the file first.
import csv
import os
with open('countries.csv', mode='r') as oldfile, open(
'countries.tmp', mode='w', newline='') as newfile:
# define a reader and a writer
reader = csv.reader(oldfile, delimiter=';', quotechar='"')
writer = csv.writer(newfile, delimiter=';', quotechar='"',
quoting=csv.QUOTE_MINIMAL)
for line in reader:
print(*line, sep=';')
# copy everything changing the third field
for line in reader:
if line[2] == "USA":
actual_price = int(line[2])
print(actual_price)
new_price = int(actual_price) * 2
print(new_price)
for row in reader:
writer.writerow([row[0], row[1], ,new_price])
# ok, time to rename the file
os.replace('countries.tmp', 'countries.csv')
Thank you for answer

You are changing new_price at every iteration of your for loop. You should therefore be writing the row within the loop where you change the value:
with open('countries.csv', mode='r') as oldfile, open('countries.tmp', mode='w', newline='') as newfile:
reader = csv.reader(oldfile, delimiter=';', quotechar='"')
writer = csv.writer(newfile, delimiter=';', quotechar='"', quoting=csv.QUOTE_MINIMAL)
for row in reader:
price = int(row[2])
if row[1] == "USA":
price = price*2
writer.writerow([row[0], row[1], price])
os.replace('countries.tmp', 'countries.csv')

I need to get only testpath1 and store this in a variable

My code:
import csv
with open("C:/Users/users/Desktop/tst/test.csv") as csv_file:
csv_reader = csv.reader(csv_file, delimiter=';')
next(csv_reader)
for line in csv_reader:
print("line[0])
but that prints only testpath1 – testpath4.

converting TXT to CSV python

I have a txt data. it looks as follows
time pos
0.02 1
0.1 2
...
and so on. so the each line is separated with a space. I need to convert it in to a CSV file. like
time,pos
0.02,1
0.1,2
0.15,3
How can I do it with python ? This is what I have tried
time = []
pos = []
def get_data(filename):
with open(filename, 'r') as csvfile:
csvFileReader = csv.reader(csvfile)
next(csvFileReader)
for row in csvFileReader:
time.append((row[0].split(' ')[0]))
pos.append((row[1]))
return

with open(filename) as infile, open('outfile.csv','w') as outfile:
for line in infile:
outfile.write(line.replace(' ',','))

From here:
import csv
with open(filename, newline='') as f:
reader = csv.reader(f, delimiter=' ')
for row in reader:
print(row)
For writing just use default options and it would save file with comma as a delimiter.

try:
import pandas as pd
with open(filename, 'r') as fo:
data = fo.readlines()
for d in range(len(data)):
if d==0:
column_headings = data[d].split()
data_to_insert = data[d].split()
pd.DataFrame(data_to_insert).to_excel('csv_file.csv', header=False, index=False, columns = column_headings))

You can use this:
import csv
time = []
pos = []
def get_data(filename):
with open(filename, 'r') as csvfile:
csvfile1 = csv.reader(csvfile, delimiter=' ')
with open(filename.replace('.txt','.csv'), 'w') as csvfile:
writer = csv.writer(csvfile, delimiter=',')
for row in csvfile1:
writer.writerow(row)

Use Python to write on specific columns in csv file

I have data in a file and I need to write it to CSV file in specific column. The data in file is like this:
002100
002077
002147
My code is this:
import csv
f = open ("file.txt","r")
with open("watout.csv", "w") as output:
for line in f :
c.writerows(line)
It is always writes on the first column. How could I resolve this?
Thanks.

This is how I solved the problem
f1 = open ("inFile","r") # open input file for reading
with open('out.csv', 'w',newline="") as f:up # output csv file
writer = csv.writer(f)
with open('in.csv','r') as csvfile: # input csv file
reader = csv.reader(csvfile, delimiter=',')
for row in reader:
row[7] = f1.readline() # edit the 8th column
writer.writerow(row)
f1.close()
python 2 users replace
with open('out.csv', 'w',newline="") as f:
by
with open('out.csv', 'wb') as f:

Taking data from text file and writing it as a .csv file in python

EDIT: Thanks for the answers guys, got what I needed!!
Basically I am trying to take what I have stored in my textfile and I am trying to write that into a .csv file. In my file are tweets that I have stored and I am trying to have one tweet in each cell in my .csv file.
Right now it is only taking one tweet and creating a .csv file with it and I need it to take all of them. Any help is greatly appreciated. Here is what I have so far.
with open('reddit.txt', 'rb') as f:
reader = csv.reader(f, delimiter=':', quoting = csv.QUOTE_NONE)
for row in reader:
print row
cr = csv.writer(open('reddit.csv', 'wb'))
cr.writerow(row)

You'll need to create the writer outside of the loop:
with open('reddit.txt', 'rb') as input_file:
reader = csv.reader(input_file, delimiter=':', quoting = csv.QUOTE_NONE)
with open('reddit.csv', 'wb') as output_file:
writer = csv.writer(output_file)
for row in reader:
writer.writerow(row)
Although here it might be cleaner to open the files without with:
input_file = open('reddit.txt', 'rb')
output_file = open('reddit.csv', 'wb')
reader = csv.reader(input_file, delimiter=':', quoting=csv.QUOTE_NONE)
writer = csv.writer(output_file)
for row in reader:
writer.writerow(row)
input_file.close()
output_file.close()
Or you can still use with and just have a really long line:
with open('reddit.txt', 'rb') as input_file, open('reddit.csv', 'wb') as output_file:
reader = csv.reader(input_file, delimiter=':', quoting = csv.QUOTE_NONE)
writer = csv.writer(output_file)
for row in reader:
writer.writerow(row)

The line cr = csv.writer(open('reddit.csv', 'wb')) is inside the for loop. You need to open the file just once, place this line after
reader = csv.reader(f, delimiter=':', quoting = csv.QUOTE_NONE)
Then write to it as you did in each loop iteration.