The ask is to sort and save a csv file in a new csv file. With the code below(below1), I seem to get the result when I open the new csv file. However, when I run the code on the homework interface, it prints out wrong (below2). Can anyone identify why it doesn't work? I have the correct solution to the ask as well (below3). I don't understand why mine doesn't work.
Below1:
import csv
def sort_records(csv_filename, new_filename):
file = open(csv_filename)
lines = file.readlines()
newfile = open(new_filename, "w")
header = lines[0]
newfile.write(header)
lines.remove(header)
lines.sort(key=lambda x: x[0])
for item in lines:
newfile.write(item)
file.close()
newfile.close()
Below2:
city/month,Jan,Feb,Mar,Apr
Brisbane,31.3,40.2,37.9,29
Darwin,34,34,33.2,34.5Melbourne,41.2,35.5,37.4,29.3
Below3:
import csv
def sort_records(csv_filename, new_filename):
csv_file = open(csv_filename)
reader = csv.reader(csv_file)
header = next(reader)
data2d = list(reader)
data2d.sort()
csv_file.close()
new_file = open(new_filename, "w")
writer = csv.writer(new_file)
writer.writerow(header)
writer.writerows(data2d)
new_file.close()
The original csv file:
city/month,Jan,Feb,Mar,Apr,May,Jun,Jul,Aug,Sep,Oct,Nov,Dec
Melbourne,41.2,35.5,37.4,29.3,23.9,16.8,18.2,25.7,22.3,33.5,36.9,41.1
Brisbane,31.3,40.2,37.9,29,30,26.7,26.7,28.8,31.2,34.1,31.1,31.2
Darwin,34,34,33.2,34.5,34.8,33.9,32,34.3,36.1,35.4,37,35.5
Perth,41.9,41.5,42.4,36,26.9,24.5,23.8,24.3,27.6,30.7,39.8,44.2
Adelaide,42.1,38.1,39.7,33.5,26.3,16.5,21.4,30.4,30.2,34.9,37.1,42.2
Canberra,35.8,29.6,35.1,26.5,22.4,15.3,15.7,21.9,22.1,30.8,33.4,35
Hobart,35.5,34.1,30.7,26,20.9,15.1,17.5,21.7,20.9,24.2,30.1,33.4
Sydney,30.6,29,35.1,27.1,28.6,20.7,23.4,27.7,28.6,34.8,26.4,30.2
There is no need for additional modules in this case. Open the input file for reading (readonly) and the output file for writing.
Write the first line (column descriptions) from input to output. Then sort the list returned from readlines and write to output.
Like this:
ORIGINAL = 'original.csv'
NEW = 'new.csv'
with open(ORIGINAL) as original, open(NEW, 'w') as new:
new.write(next(original))
new.writelines(sorted(original.readlines(), key=lambda x: x.split(',')[0]))
I've run your code on my machine and it works as it's supposed to. Is it possible to print out the CSV file from this homework interface before sorting?
What I am trying to do is remove the quotes while writing the data to a new CSV file.
I have tried using s.splits, and .replaces with no luck. Can you guys point me in the right direction?
Current Code:
def createParam():
with open('testcsv.csv', 'r') as f:
reader = csv.reader(f)
csvList = list(reader)
for item in csvList:
os.mkdir(r"C:\Users\jefhill\Desktop\Test Path\\" + item[0])
with open(r"C:\Users\jefhill\Desktop\Test Path\\" + item[0] + r"\prm.263", "w+") as f:
csv.writer(f).writerow(item[1:])
f.close
Data within testcsv.csv:
0116,"139,data1"
0123,"139,data2"
0130,"35,data678"
Data output when script is ran (in each individual file):
"139,data1"
"139,data2"
"35,data678"
Data I would like:
139,data1
139,data2
35,data678
You can use str.replace to replace the " (double quotes) with '' (null).
Then split and print all but first item in the list.
with open('outputfile.csv', w) as outfile: # open the result file to be written
with open('testcsv.csv', 'r') as infile: # open the input file
for line in infile: # iterate through each line in input file
newline = line.replace('"', '') # replace double quotes with no space
outfile.write(newline.split(',',maxsplit=1)[1]) # write second element to output file after splitting the newline once
You don't need f.close() when you use with open...
Currently, I take in a csv file using custom delimiters, "|". I then read it in and modify it using the code below:
import csv
ChangedDate = '2018-10-31'
firstfile = open('example.csv',"r")
firstReader = csv.reader(firstfile, delimiter='|')
firstData = list(firstReader)
outputFile = open("output.csv","w")
iteration = 0
for row in firstData:
firstData[iteration][25] = ChangedDate
iteration+=1
outputwriter = csv.writer(open("output.csv","w"))
outputwriter.writerows(firstData)
outputFile.close()
However, when I write the rows to my output file, they are comma seperated. This is a problem because I am dealing with large financial data, and therefore commas appear naturally, such as $8,000.00, hence the "|" delimiters of the original file. Is there a way to "re-delimit" my list before I write it to an output file?
You can provide the delimiter to the csv.writer:
with open("output.csv", "w") as f:
outputwriter = csv.writer(f, delimiter='|')
I want to end each interation of a for loop with writing a new line of content (including newline) to a csv file. I have this:
# Set up an output csv file with column headers
with open('outfile.csv','w') as f:
f.write("title; post")
f.write("\n")
This does not appear to write an actual \n (newline) the file. Further:
# Concatenate into a row to write to the output csv file
csv_line = topic_title + ";" + thread_post
with open('outfile.csv','w') as outfile:
outfile.write(csv_line + "\n")
This, also, does not move the cursor in the outfile to the next line. Each new line, with every iteration of the loop, just overwrites the most recent one.
I also tried outfile.write(os.linesep) but did not work.
change 'w' to 'a'
with open('outfile.csv','a')
with open('outfile.csv', 'w', newline='') as f:
f.writerow(...)
Alternatively:
f = csv.writer('outfile.csv', lineterminator='\n')
I confront with same problem， only need follow:
f = csv.writer('outfile.csv', lineterminator='\n')
If your using python2 then use
with open('xxx.csv', 'a') as f:
writer = csv.writer(f)
writer.writerow(fields)
If you are using python3 make use of newline=''
Please try with: open(output_file_name.csv, 'a+', newline='') as f:
I have written the following to isolate a very specific part of a file:
for line in open('120301.KAP'):
rec = line.strip()
if rec.startswith('PLY'):
print line
The output appears as such
PLY/1,48.107478621032,-69.733975000000
PLY/2,48.163516399836,-70.032838888053
PLY/3,48.270000002883,-70.032838888053
PLY/4,48.270000002883,-69.712824977522
PLY/5,48.192379262383,-69.711801581207
PLY/6,48.191666671083,-69.532840015422
PLY/7,48.033358898628,-69.532840015422
PLY/8,48.033359033880,-69.733975000000
PLY/9,48.107478621032,-69.733975000000
Ideally what I am hoping for is the output to create a CSV file with just the coordinates. The PLY/1, PLY/2, etc. does not need to stay.
Is this doable? If not, at least can the print statements result in a new text file with the same name as the KAP file?
You can use the csv module:
import csv
with open('120301.csv', 'w', newline='') as file:
writer = csv.writer(file)
for line in open('120301.KAP'):
rec = line.strip()
if rec.startswith('PLY'):
writer.writerow(rec.split(','))
In a similar way, the csv.reader can easily read records from your input file.
https://docs.python.org/3/library/csv.html?highlight=csv#module-contents
If you are using Python 2.x, you should open the file in binary mode:
import csv
with open('120301.csv', 'wb') as file:
writer = csv.writer(file)
for line in open('120301.KAP'):
rec = line.strip()
if rec.startswith('PLY'):
writer.writerow(rec.split(','))
You could open the file at the beginning of your code and then just add a write statement after the print line.
Something like this:
target = open(filename, 'w')
for line in open('120301.KAP'):
rec = line.strip()
if rec.startswith('PLY'):
print line
target.write(line)
target.write("\n") #writes a new line
This is totally doable!
Here are a couple of links to some docs for writing/reading CSV:
https://docs.python.org/2/library/csv.html
You could also just make your own CSV with the regular file reading/writing functions.
file = open('data', rw)
output = open('output.csv', w)
file.write('your infos') #add a comma to each string you output?
The simplest way is to redirect stdout to a file:
for i in range(10):
print str(i) + "," + str(i*2)
will output:
0,0
1,2
2,4
3,6
4,8
5,10
6,12
7,14
8,16
9,18
if you run it as python myprog.py > myout.txt the result go to myout.txt