Develop Reference

List to csv without commas in Python

I have a following problem.
I would like to save a list into a csv (in the first column).
See example here:
import csv
mylist = ["Hallo", "der Pixer", "Glas", "Telefon", "Der Kühlschrank brach kaputt."]
def list_na_csv(file, mylist):
with open(file, "w", newline="") as csv_file:
csv_writer = csv.writer(csv_file)
csv_writer.writerows(mylist)
list_na_csv("example.csv", mylist)
My output in excel looks like this:
Desired output is:
You can see that I have two issues: Firstly, each character is followed by comma. Secondly, I don`t know how to use some encoding, for example UTF-8 or cp1250. How can I fix it please?
I tried to search similar question, but nothing worked for me. Thank you.

You have two problems here.
writerows expects a list of rows, said differently a list of iterables. As a string is iterable, you write each word in a different row, one character per field. If you want one row with one word per field, you should use writerow
csv_writer.writerow(mylist)
by default, the csv module uses the comma as the delimiter (this is the most common one). But Excel is a pain in the ass with it: it expects the delimiter to be the one of the locale, which is the semicolon (;) in many West European countries, including Germany. If you want to use easily your file with your Excel you should change the delimiter:
csv_writer = csv.writer(csv_file, delimiter=';')
After your edit, you want all the data in the first column, one element per row. This is kind of a decayed csv file, because it only has one value per record and no separator. If the fields can never contain a semicolon nor a new line, you could just write a plain text file:
...
with open(file, "w", newline="") as csv_file:
for row in mylist:
print(row, file=file)
...
If you want to be safe and prevent future problems if you later want to process more corner cases values, you could still use the csv module and write one element per row by including it in another iterable:
...
with open(file, "w", newline="") as csv_file:
csv_writer = csv.writer(csv_file, delimiter=';')
csv_writer.writerows([elt] for elt in mylist)
...

l = ["Hallo", "der Pixer", "Glas", "Telefon", "Der Kühlschrank brach kaputt."]
with open("file.csv", "w") as msg:
msg.write(",".join(l))
For less trivial examples:
l = ["Hallo", "der, Pixer", "Glas", "Telefon", "Der Kühlschrank, brach kaputt."]
with open("file.csv", "w") as msg:
msg.write(",".join([ '"'+x+'"' for x in l]))
Here you basically set every list element between quotes, to prevent from the intra field comma problem.

Try this it will work 100%
import csv
mylist = ["Hallo", "der Pixer", "Glas", "Telefon", "Der Kühlschrank brach kaputt."]
def list_na_csv(file, mylist):
with open(file, "w") as csv_file:
csv_writer = csv.writer(csv_file)
csv_writer.writerow(mylist)
list_na_csv("example.csv", mylist)

If you want to write the entire list of strings to a single row, use csv_writer.writerow(mylist) as mentioned in the comments.
If you want to write each string to a new row, as I believe your reference to writing them in the first column implies, you'll have to format your data as the class expects: "A row must be an iterable of strings or numbers for Writer objects". On this data that would look something like:
csv_writer.writerows((entry,) for entry in mylist)
There, I'm using a generator expression to wrap each word in a tuple, thus making it an iterable of strings. Without something like that, your strings are themselves iterables and lead to it delimiting between each character as you've seen.
Using csv to write a single entry per line is almost pointless, but it does have the advantage that it will escape your delimiter if it appears in the data.
To specify an encoding, the docs say:
Since open() is used to open a CSV file for reading, the file will by
default be decoded into unicode using the system default encoding (see
locale.getpreferredencoding()). To decode a file using a different
encoding, use the encoding argument of open:
import csv with open('some.csv', newline='', encoding='utf-8') as f:
reader = csv.reader(f)
for row in reader:
print(row)
The same applies to writing in something other than the system default encoding: specify the encoding argument when
opening the output file.

try split("\n")
example:
counter = 0
amazing list = ["hello","hi"]
for x in titles:
ok = amazinglist[counter].split("\n")
writer.writerow(ok)
counter +=1

Remove 1000's separator from column in CSV?

I have a Python script where I'm importing a csv that has commas in values over 1000. These values are strings in the csv. I need to remove the commas from the values, and convert the strings to rounded floats inside the csv before it's imported into Python.
I've tried appending all the new values to a list to use the csv.writer, but I haven't been able to figure out how to have the writer only replace the values in the column that have commas. Here's what I have so far. :
import csv
RoomReport = r'path_to_csv'
new_values_list = []
f = open(RoomReport, "r")
reader = csv.reader(f)
writer = csv.writer(f)
for row in reader:
useable_area = row[7]
if "," in useable_area:
useable_area_no_comma = useable_area.replace(",","")
useable_area_rounded = int(round(float(useable_area_no_comma)))
new_values_list.append(useable_area_rounded)
f.close()

As I mentioned in a comment, this can only be done if the input csv file is formatted in a way that will allow the commas in the numbers to be differentiated from the commas between each one of them.
Here's an example of one way it could be done (by quoting all the values):
"0","1","2","3","4","5","6","7,123.6","8","9"
"0","1","2","3","4","5","6","1,000","8","9"
"0","1","2","3","4","5","6","20,000","8","9"
Here's code that will do what you want. It uses the locale.atof function to simplify cleaning up the number:
import csv
import locale
# Set local to someplace that uses a comma for the thousands separator.
locale.setlocale(locale.LC_ALL, 'English_US.1252')
RoomReport = r'RoomReport.csv'
cleaned_report = r'RoomReport_cleaned.csv'
new_values_list = []
with open(RoomReport, "r", newline='') as inp:
for row in csv.reader(inp):
if "," in row[7]:
row[7] = int(round(locale.atof(row[7])))
new_values_list.append(row)
# Create cleaned-up output file.
with open(cleaned_report, "w", newline='') as outp:
csv.writer(outp, quoting=csv.QUOTE_ALL).writerows(new_values_list)
The RoomReport_cleaned.csv it creates from the example input will contain this:
"0","1","2","3","4","5","6","7124","8","9"
"0","1","2","3","4","5","6","1000","8","9"
"0","1","2","3","4","5","6","20000","8","9"
Note that since the values in the output no longer have commas embedded in them, the quoting all fields is not longer necessary—so could be left out by not specifying csv.QUOTE_ALL.

maybe something like this?
import re
from sys import stdout
isnum = re.compile('^[0-9, ]+$')
non = re.compile('[, ]')
fd = StringIO()
out = csv.writer(fd)
out.writerow(['foo','1,000,000',19])
out.writerow(['bar','1,234,567',20])
fd.seek(0)
inp = csv.reader(fd)
out = csv.writer(stdout)
for row in inp:
for i, x in enumerate(row):
if isnum.match(x):
row[i] = float(non.sub('', x))
out.writerow(row)

how can I use csv tools for zip text file?

update-my file.txt.zp is tab delimited and looks kind of like this :
file.txt.zp
I want to split the first col by : _ /
original post:
I have a very large zipped tab delimited file.
I want to open it, scan it one row at a time, split some of the col, and write it to a new file.
I got various errors (every time I fix one another pops)
This is my code:
import csv
import re
import gzip
f = gzip.open('file.txt.gz')
original = f.readlines()
f.close()
original_l = csv.reader(original)
for row in original_l:
file_l = re.split('_|:|/',row)
with open ('newfile.gz', 'w', newline='') as final:
finalfile = csv.writer(final,delimiter = ' ')
finalfile.writerow(file_l)
Thanks!
for this code i got the error:
for row in original_l:
_csv.Error: iterator should return strings, not bytes (did you open the file in text mode?)
so based on what I found here I added this after f.close():
original = original.decode('utf8')
and then got the error:
original = original.decode('utf8')
AttributeError: 'list' object has no attribute 'decode'

Update 2
This code should produce the output that you're after.
import csv
import gzip
import re
with gzip.open('file.txt.gz', mode='rt') as f, \
open('newfile.gz', 'w') as final:
writer = csv.writer(final, delimiter=' ')
reader = csv.reader(f, delimiter='\t')
_ = next(reader) # skip header row
for row in reader:
writer.writerow(re.split(r'_|:|/', row[0]))
Update
Open the gzip file in text mode because str objects are required by the CSV module in Python 3.
f = gzip.open('file.txt.gz', 'rt')
Also specify the delimiter when creating the csv.reader.
original_l = csv.reader(original, delimiter='\t')
This will get you past the first hurdle.
Now you need to explain what the data is, which columns you wish to extract, and what the output should look like.
Original answer follows...
One obvious problem is that the output file is constantly being overwritten by the next row of input. This is because the output file is opened in (over)write mode (`'w`` ) once per row.
It would be better to open the output file once outside of the loop.
Also, the CSV file delimiter is not specified when creating the reader. You said that the file is tab delimited so specify that:
original_l = csv.reader(original, delimiter='\t')
On the other hand, your code attempts to split each row using other delimiters, however, the rows coming from the csv.reader are represented as a list, not a string as the re.split() code would require.
Another problem is that the output file is not zipped as the name suggests.

Convert from space to comma and reorder the values Python

I have a .csv file with many lines and with the structure:
YYY-MM-DD HH first_name quantity_number second_name first_number second_number third_number
I have a script in python to convert the separator from space to comma, and that working fine.
import csv
with open('file.csv') as infile, open('newfile.dat', 'w') as outfile:
for line in infile:
outfile.write(" ".join(line.split()).replace(' ', ','))
I need change, in the newfile.dat, the position of each value, for example put the HH value in position 6, the second_name value in position 2, etc.
Thanks in advance for your help.

If you're import csv might as well use it
import csv
with open('file.csv', newline='') as infile, open('newfile.dat', 'w+', newline='') as outfile:
read = csv.reader(infile, delimiter=' ')
write = csv.writer(outfile) #defaults to excel format, ie commas
for line in read:
write.writerow(line)
Use newline='' when opening csv files, otherwise you get double spaced files.
This just writes the line as it is in the input. If you want to change it before writing, do it in the for line in read: loop. line is a list of strings, which you can change the order of in any number of ways.
One way to reorder the values is to use operator.itemgetter:
from operator import itemgetter
getter = itemgetter(5,4,3,2,1,0) #This will reverse a six_element list
for line in read:
write.writerow(getter(line))

To reorder the items, a basic way could be as follows:
split_line = line.split(" ")
column_mapping = [9,6,3,7,3,2,1]
reordered = [split_line[c] for c in column_mapping]
joined = ",".join(reordered)
outfile.write(joined)
This splits up the string, reorders it according to column_mapping and then combines it back into one string (comma separated)
(in your code don't include column_mapping in the loop to avoid reinitialising it)

python csv replace listitem

i have following output from a csv file:
word1|word2|word3|word4|word5|word6|01:12|word8
word1|word2|word3|word4|word5|word6|03:12|word8
word1|word2|word3|word4|word5|word6|01:12|word8
what i need to do is change the time string like this 00:01:12.
my idea is to extract the list item [7] and add a "00:" as string to the front.
import csv
with open('temp', 'r') as f:
reader = csv.reader(f, delimiter="|")
for row in reader:
fixed_time = (str("00:") + row[7])
begin = row[:6]
end = row[:8]
print begin + fixed_time +end
get error message:
TypeError: can only concatenate list (not "str") to list.
i also had a look on this post.
how to change [1,2,3,4] to '1234' using python
i neeed to know if my approach to soloution is the right way. maybe need to use split or anything else for this.
thx for any help

The line that's throwing the exception is
print begin + fixed_time +end
because begin and end are both lists and fixed_time is a string. Whenever you take a slice of a list (that's the row[:6] and row[:8] parts), a list is returned. If you just want to print it out, you can do
print begin, fixed_time, end
and you won't get an error.
Corrected code:
I'm opening a new file for writing (I'm calling it 'final', but you can call it whatever you want), and I'm just writing everything to it with the one modification. It's easiest to just change the one element of the list that has the line (row[6] here), and use '|'.join to write a pipe character between each column.
import csv
with open('temp', 'r') as f, open('final', 'w') as fw:
reader = csv.reader(f, delimiter="|")
for row in reader:
# just change the element in the row to have the extra zeros
row[6] = '00:' + row[6]
# 'write the row back out, separated by | characters, and a new line.
fw.write('|'.join(row) + '\n')

you can use regex for that:
>>> txt = """\
... word1|word2|word3|word4|word5|word6|01:12|word8
... word1|word2|word3|word4|word5|word6|03:12|word8
... word1|word2|word3|word4|word5|word6|01:12|word8"""
>>> import re
>>> print(re.sub(r'\|(\d\d:\d\d)\|', r'|00:\1|', txt))
word1|word2|word3|word4|word5|word6|00:01:12|word8
word1|word2|word3|word4|word5|word6|00:03:12|word8
word1|word2|word3|word4|word5|word6|00:01:12|word8