Reading and writing data from/to csv file. When I run the program its formatted correctly in the console window, however, the formatting is off in the csv file I'm writing to (has a comma after each letter). What am I missing here?
import csv
with open("WJU stats.csv", 'r') as csv_file:
csv_reader = csv.reader(csv_file)
with open('wjudata.csv', 'w') as new_file:
csv_writer = csv.writer(new_file)
for row in csv_reader:
csv_writer.writerow(row[0])
print(row[0])
The function writerow takes an iterable, for example a list, so it writes each element of the iterable to the file in a comma separated row. The thing is strings are also iterables which elements are characters. If you want a single column csv you should use
csv_writer.writerow([row[0]])
Related
I have some vocabulary and their counterparts to create an Anki deck. I need the program to write the output of my code in two columns of a csv file; first for the vocabulary and second for the meaning. I've tried two codes but neither of them worked. How can I solve this problem?
Notebook content(vocab):
obligatory,義務的
sole,単独,唯一
defined,一定
obey,従う
...
First try:
with open("C:/Users/berka/Desktop/Vocab.txt") as csv_file:
csv_reader = csv.reader(csv_file)
with open("C:/Users/berka/Desktop/v.csv", "w", newline="") as new_file:
csv_writer = csv.writer(new_file, delimiter=",")
for line in csv_reader:
csv_writer.writerow(line)
Second try:
with open("C:/Users/berka/Desktop/Vocab.txt") as csv_file:
csv_reader = csv.DictReader(csv_file)
with open("C:/Users/berka/Desktop/v.csv", "w",) as f:
field_names = ["Vocabulary", "Meaning"]
csv_writer = csv.DictWriter(f, fieldnames=field_names, extrasaction="ignore")
csv_writer.writeheader()
for line in csv_reader:
csv_writer.writerow(line)
Result of the first try:
https://cdn.discordapp.com/attachments/696432733882155138/746404430123106374/unknown.png
#Second try was not even close
Expected result:
https://cdn.discordapp.com/attachments/734460259560849542/746432094825087086/unknown.png
Like Kevin said, Excel uses ";" as delimiter and your csv code creates a csv file with comma(,) delimiter. That's why it's shown with commas in your Csv Reader. You can pass ";" as delimiter if you want Excel to read your file correctly. Or you can create a csv file with your own Csv Reader and read it with notepad if you want to see which delimiter it uses.
Your first try works, it's the app you're using for importing that is not recognizing the , as the delimiter. I'm not sure where you're importing this to, but at least in Google Sheets you can choose what the delimiter is, even after the fact.
As per the title, I'm attempting to write a python script to read a csv file, filter through it to see which ones I need and output the filtered rows into a seperate csv file.
So far I am able to read the csv files with:
open('list.csv') as f
csv_f = csv.reader(f)
and I am storing 3 of the rows in a tuple and using it to compare it to another list to see if there is a match. If there is a match I want the row containing the tuple to output to a new csv file.
I have successfully been able to read the files, match the tuples with another list and output which have been matched as text. The problem is I do not know how to then output the rows that match the tuple into a new csv file.
I was thinking to assign a row number to each tuple but that did not go anywhere either.
I want to know the best way I can effectively output the rows I need
Using csv module, this could be a solution more elegant:
with open('input.csv', 'r') as inp, open('output', 'w') as outp:
csv_f = csv.reader(inp)
csv_o = csv.reader(outp)
for line in csv_f:
if line == 'something':
csv_o.writeline(line)
Open both files. Iterate through the lines in the file that you read from and case your condition evaluates to True, then write the line to the output file.
with open('list.csv', 'r') as rf:
with open('output.csv', 'w') as wf:
# Read lines
for read_line in rf:
if <your condition>:
# Write to the file
wf.write(read_line)
I was just wondering what this line of code does:
writerow([recordlist[i][0], recordlist[i][1], recordlist[i][2]])
I know its a parameter of some sort, but what does it actually do in all of this code:
recordlist=[["1",chinese, "male"],["2",indian, "female"]]
import math
import csv
file_name = 'info.txt'
ofile = open(file_name, 'a')
writer = csv.writer(ofile, delimiter=',', lineterminator='\n')
for i in range(0,len(recordlist)):
writer.writerow([recordlist[i][0], recordlist[i][1], recordlist[i][2]])
ofile.close()
Thank you!
You've created a csvwriter. It has a method writerow that takes a sequence (list, tuple, etc.) of values to write the underlying file in delimited format, which in this case uses a comma as the delimiter. So it will create a row in the csv file for each row in the recordlist variable, as it iterates over it in the for loop. Each row will consist of the values defined on the first line of your code, separated by commas.
The real answer should be "run it and try it" to see what it does.
Then read the documentation of the csv module in Python here
I am trying to append several csv files into a single csv file using python while adding the file name (or, even better, a sub-string of the file name) as a new variable. All files have headers. The following script does the trick of merging the files, but does not cover the file name as variable issue:
import glob
filenames=glob.glob("/filepath/*.csv")
outputfile=open("out.csv","a")
for line in open(str(filenames[1])):
outputfile.write(line)
for i in range(1,len(filenames)):
f = open(str(filenames[i]))
f.next()
for line in f:
outputfile.write(line)
outputfile.close()
I was wondering if there are any good suggestions. I have about 25k small size csv files (less than 100KB each).
You can use Python's csv module to parse the CSV files for you, and to format the output. Example code (untested):
import csv
with open(output_filename, "wb") as outfile:
writer = None
for input_filename in filenames:
with open(input_filename, "rb") as infile:
reader = csv.DictReader(infile)
if writer is None:
field_names = ["Filename"] + reader.fieldnames
writer = csv.DictWriter(outfile, field_names)
writer.writeheader()
for row in reader:
row["Filename"] = input_filename
writer.writerow(row)
A few notes:
Always use with to open files. This makes sure they will get closed again when you are done with them. Your code doesn't correctly close the input files.
CSV files should be opened in binary mode.
Indices start at 0 in Python. Your code skips the first file, and includes the lines from the second file twice. If you just want to iterate over a list, you don't need to bother with indices in Python. Simply use for x in my_list instead.
Simple changes will achieve what you want:
For the first line
outputfile.write(line) -> outputfile.write(line+',file')
and later
outputfile.write(line+','+filenames[i])
import csv, Tkinter
with open('most_common_words.csv') as csv_file: # Opens the file in a 'closure' so that when it's finished it's automatically closed"
csv_reader = csv.reader(csv_file) # Create a csv reader instance
for row in csv_reader: # Read each line in the csv file into 'row' as a list
print row[0] # Print the first item in the list
I'm trying to import this list of most common words using csv. It continues to give me the same error
for row in csv_reader: # Read each line in the csv file into 'row' as a list
Error: new-line character seen in unquoted field - do you need to open the file in universal-newline mode?
I've tried a couple different ways to do it as well, but they didn't work either. Any suggestions?
Also, where does this file need to be saved? Is it okay just being in the same folder as the program?
You should always open a CSV file in binary mode (Python 2) or universal newline mode (Python 3). Also, make sure that the delimiters and quote characters are , and ", or you'll need to specify otherwise:
with open('most_common_words.csv', 'rb') as csv_file:
csv_reader = csv.reader(csv_file, delimiter=';', quotechar='"') # for EU CSV
You can save the file in the same folder as your program. If you don't, you can provide the correct path to open() as well. Be sure to use raw strings if you're on Windows, otherwise the backslashes may trick you: open(r"C:\Python27\data\table.csv")
It seems you have a file with one column as you say here:
It is a simple list of words. When I open it up, it opens into Excel
with one column and 500 rows of 500 different words.
If so, you don't need the csv module at all:
with open('most_common_words.csv') as f:
rows = list(f)
Note in this case, each item of the list will have the newline appended to it, so if your file is:
apple
dog
cat
rows will be ['apple\n', 'dog\n', 'cat\n']
If you want to strip the end of line, then you can do this:
with open('most_common_words.csv') as f:
rows = list(i.rstrip() for i in f)