I am very new to Python programming and decided on a small project to learn the language.
Basically I am trying to:
Read the first cell of a CSV file.
Ask if that cell value is "liked".
If liked, write to the column next to the cell on 1., "1".
Else, write "0".
Repeat on next row until end of list.
My code right now:
import csv
reader = csv.reader(open("mylist.csv"), delimiter=',')
data = []
for row in reader:
data.append(row)
ask = (data[0][0])
ans = input("Do you like {}? ".format(ask))
if ans == ("y"):
f = open('mylist.csv', 'r')
reader = csv.reader(f)
data = list(reader)
f.close()
data[0][1] = '1'
my_new_list = open('mylist.csv', 'w', newline='')
csv_writer = csv.writer(my_new_list)
csv_writer.writerows(data)
my_new_list.close()
else:
f = open('mylist.csv', 'r')
reader = csv.reader(f)
data = list(reader)
f.close()
data[0][1] = '0'
my_new_list = open('mylist.csv', 'w', newline='')
csv_writer = csv.writer(my_new_list)
csv_writer.writerows(data)
my_new_list.close()
So basically, I am stuck trying to get the content of the next row.
FYI, I am looking to implement machine learning to this process.
First learning how to do this in a basic manner.
Any help is welcome.
Thank you!
You shouldn't read from and write to the same file/list/dict at the same time. If you do, references to data may change. You can start with something like this for your task. However, note that as the file grows you code becomes slower.
import csv
reader = csv.reader(open("test.csv", 'r'), delimiter=',')
content = []
for row in reader:
item = row[0]
ans = raw_input("Do you like {}? ".format(item))
if ans == 'y':
content.append([item, 1])
else:
content.append([item, 0])
writer = csv.writer(open('test.csv', 'w'))
writer.writerows(content)
In my last work with csv I opened the file so:
import csv
with open(name) as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
data.append(row)
If you want the resultant csv file to contain all of the data from the input file but with the question results added in, you could use something like this.
It will insert you answer (0 or 1) after the first item in each record.
import csv
reader = csv.reader(open("mylist.csv", 'r'), delimiter=',')
data = []
for row in reader:
data.append(row)
for row in data:
ans = raw_input("Do you like {}? ".format(row[0]))
if ans == 'y':
row[1:1] = "1"
else:
row[1:1] = "0"
writer = csv.writer(open('myresult.csv', 'w'))
writer.writerows(data)
Related
I want to create a program which generates numbers from 0 to 100000 and stores it in a file then, remove the numbers i give as input
I have done the code for generating the numbers and storing them in a csv file
import csv
nums = list(range(0,100000))
with open('codes.csv', 'w') as f:
writer = csv.writer(f)
for val in nums:
writer.writerow([val])
and i tried to delete the row i wanted with this
import csv
import os
lines = list()
while True:
members= input("Please enter a number to be deleted: ")
with open('codes.csv', 'r') as readFile:
reader = csv.reader(readFile)
for row in reader:
lines.append(row)
for field in row:
if field == members:
lines.remove(row)
os.remove('codes.csv')
with open('codes.csv', 'a+') as writeFile:
writer = csv.writer(writeFile)
writer.writerows(lines)
but the file size is multiplying each time i remove a number, please help
Add check before appending to your list, something like this should work:
with open('codes.csv', 'r') as readFile:
reader = csv.reader(readFile)
for row in reader:
if all(field != members for field in row):
lines.append(row)
Ps: don't forget to clear lines by adding lines = [] at the beginning of the while loop (I assume you know what you're doing).
There a two problems:
The lines list is never cleared. Whenever a number is entered, everything is written again to lines.
When writing, the file is opened with the a+ attributes, which means "append and update" file.
Try to recreate the list within the outer while loop and override the file contents by opening the file with attribute w, like this:
import csv
import os
while True:
members= input("Please enter a number to be deleted: ")
lines = list()
with open('codes.csv', 'r') as readFile:
reader = csv.reader(readFile)
for row in reader:
lines.append(row)
for field in row:
if field == members:
lines.remove(row)
os.remove('codes.csv')
with open('codes.csv', 'w') as writeFile:
writer = csv.writer(writeFile)
writer.writerows(lines)
I'm trying to read a csv file in Python using the module csv.
To do that, I use a reader variable :
with open('oneOrganization.csv', 'r', newline='') as csvfile2:
reader2 = csv.DictReader(csvfile2, delimiter=',')
for row in reader2:
if row["role"] == []:
row_dict['Role'] = "User"
else:
row_dict['Role'] = row["role"]
However, running the program, I realize that it does get in the loop at all although the cvs file exists and is indeed called oneOrganization.csv. What could be the reason of that ?
I'm starting in Python, usually this method works.
The problem that prevents your code from accessing the if loop if row['Role']==[] is because you're trying to find empty elements the wrong way.
try this instead:
Method 1:
with open('oneOrganization.csv','r') as file:
reader = csv.DictReader(file,delimiter=',')
my_list = list(reader)
for row in reader:
if row['test1'] in (None,''): # to check if cell is empty
row_dict['Role'] = "User"
else:
row_dict['Role'] = row["role"]
Method 2: provided by #Jean-François Fabre
with open('oneOrganization.csv','r') as file:
reader = csv.DictReader(file,delimiter=',')
for row in reader:
if not row['test1']:
row_dict['Role'] = "User"
else:
row_dict['Role'] = row["role"]
Method 3 : "elegant one liner" - by #Jean-François Fabre
with open('oneOrganization.csv','r') as file:
reader = csv.DictReader(file,delimiter=',')
for row in reader:
row_dict['Role'] = row["role"] or "User"
I tried it on a csv example that can be represented like this: (np.array form)
[['test1' 'test2' 'test3']
[ 1 2 3 ]
[ 11 22 33 ]
[ 222 333]]
and used this code:
import csv
with open('test_csv.csv','r') as file:
reader = csv.DictReader(file,delimiter=',')
for row in reader:
if row['test1'] in (None,''):
print('no')
else:
print(row['test1'])
or with method 2:
import csv
with open('test_csv.csv','r') as file:
reader = csv.DictReader(file,delimiter=',')
for row in reader:
if not row['test1']:
print('no')
else:
print(row['test1'])
or method 3
import csv
with open('test_csv.csv','r') as file:
reader = csv.DictReader(file,delimiter=',')
for row in reader:
print(row['test1'] or 'no')
output:
1
11
no
you can refer to this topic for more informations about how to check if a "cell" is empty in a csv file.
I have a .csv file with some data that i would like to change.
It looks like this:
item_name,item_cost,item_priority,item_required,item_completed
item 1,11.21,2,r
item 2,411.21,3,r
item 3,40.0,1,r,c
My code runs most of what i need but i am unsure of how to write back on my .csv to produce this result
item_name,item_cost,item_priority,item_required,item_completed
item 1,11.21,2,x
item 2,411.21,3,r
item 3,40.0,1,r,c
My code:
print("Enter the item number:")
line_count = 0
marked_item = int(input())
with open("items.csv", 'r') as f:
reader = csv.DictReader(f, delimiter=',')
for line in reader:
if line["item_required"] == 'r':
line_count += 1
if marked_item == line_count:
new_list = line
print(new_list)
for key, value in new_list.items():
if value == "r":
new_list['item_required'] = "x"
print(new_list)
with open("items.csv", 'a') as f:
writer = csv.writer(f)
writer.writerow(new_list.values())
There are several problems here
you're using a DictReader, which is good to read data, but not as good to read and write data as the original file, since dictionaries do not ensure column order (unless you don't care, but most of the time people don't want columns to be swapped). I just read the title, find the index of the column title, and use this index in the rest of the code (no dicts = faster)
when you write you append to the csv. You have to delete old contents, not append. And use newline='' or you get a lot of blank lines (python 3) or "wb" (python 2)
when you read, you need to store all values, not only the one you want to change, or you won't be able to write back all the data (since you're replacing the original file)
when you modify, you do overcomplex stuff I just replaced by a simple replace in list at the given index (after all you want to change r to x at a given row)
Here's the fixed code taking all aforementioned remarks into account
EDIT: added the feature you request after: add a c after x if not already there, extending the row if needed
import csv
line_count = 0
marked_item = int(input())
with open("items.csv", 'r') as f:
reader = csv.reader(f, delimiter=',')
title = next(reader) # title
idx = title.index("item_required") # index of the column we target
lines=[]
for line in reader:
if line[idx] == 'r':
line_count += 1
if marked_item == line_count:
line[idx] = 'x'
# add 'c' after x (or replace if column exists)
if len(line)>idx+1: # check len
line[idx+1] = 'c'
else:
line.append('c')
lines.append(line)
with open("items.csv", 'w',newline='') as f:
writer = csv.writer(f,delimiter=',')
writer.writerow(title)
writer.writerows(lines)
Using pandas:
import pandas as pd
df = pd.read_csv("items.csv")
print("Enter the item number:")
marked_item = int(input())
df.set_value(marked_item - 1, 'item_required', 'x')
# This is the extra feature you required:
df.set_value(marked_item - 1, 'item_completed', 'c')
df.to_csv("items.csv", index = False)
Result when marked_item = 1:
item_name,item_cost,item_priority,item_required,item_completed
item 1,11.21,2,x,c
item 2,411.21,3,r,
item 3,40.0,1,r,c
Note that according to RFC4180 you should keep the trailing commas.
I guess this should do the trick:
Open a file which can read and written to update it (use "+r" for that)
instead of opening it again write it right there using csvfilewriter, which we create at the start.
file.py
import csv
fieldnames = ["item_name","item_cost","item_priority","item_required","item_completed"]
csvfile = open("items.csv", 'r+')
csvfilewriter = csv.DictWriter(csvfile, fieldnames=fieldnames,dialect='excel', delimiter=',')
csvfilewriter.writeheader()
print("Enter the item number:")
line_count = 0
marked_item = int(input())
with open("items.csv", 'r') as f:
reader = csv.DictReader(f, delimiter=',')
for line in reader:
if line["item_required"] == 'r':
line_count += 1
if marked_item == line_count:
new_list = line
print(new_list)
for key, value in new_list.items():
if value == "r":
new_list['item_required'] = "x"
print(new_list)
csvfilewriter.writerow(new_list)
If you don't want to update the csv but want to write a new one, below is the code:
import csv
fieldnames = ["item_name","item_cost","item_priority","item_required","item_completed"]
csvfile = open("items_new.csv", 'w')
csvfilewriter = csv.DictWriter(csvfile, fieldnames=fieldnames,dialect='excel', delimiter=',')
csvfilewriter.writeheader()
print("Enter the item number:")
line_count = 0
marked_item = int(input())
with open("items.csv", 'r') as f:
reader = csv.DictReader(f, delimiter=',')
for line in reader:
if line["item_required"] == 'r':
line_count += 1
if marked_item == line_count:
new_list = line
print(new_list)
for key, value in new_list.items():
if value == "r":
new_list['item_required'] = "x"
print(new_list)
csvfilewriter.writerow(new_list)
else:
csvfilewriter.writerow(line)
I have a CSV file names.csv
First_name, Last_name
Mike, Hughes
James, Tango
, Stoke
Jack,
....etc
What I want is to be able to take the first letter of the First_name and the full Last_name and output it on screen as usernames but not include the people with First_name and Last_name property's empty. I'm completely stuck any help would be greatly appreciated
import csv
ifile = open('names.csv', "rb")
reader = csv.reader(ifile)
rownum = 0
for row in reader:
if rownum == 0:
header = row
else:
colnum = 0
for col in row:
print '%-8s: %s' % (header[colnum], col)
colnum += 1
rownum += 1
ifile.close()
Attempt #2
import csv
dataFile = open('names.csv','rb')
reader = csv.reader(dataFile)
next(reader, None)
for row in reader:
if (row in reader )
print (row[0])
I haven't saved many attempts because none of them have worked :S
import csv
dataFile = open('names.csv','rb')
reader = csv.reader(dataFile, delimiter=',', quoting=csv.QUOTE_NONE)
for row in reader:
if not row[0] or not row[1]:
continue
print (row[0][0] + row[1]).lower()
Or
import csv
dataFile = open('names.csv','rb')
reader = csv.reader(dataFile, delimiter=',', quoting=csv.QUOTE_NONE)
[(row[0][0] + row[1]).lower() for row in reader if
row[0] and row[1]]
Once you get the text from the .csv you can use the split() function to break up the text by the new lines. Your sample text is a little inconsistent, but if I understand you question correctly you can say
import csv
dataFile = open('names.csv','rb')
reader = csv.reader(dataFile)
reader = reader.split('\n')
for x in reader
print(reader[x])
Or if you want to break it up by commas just replace the '\n' with ','
Maybe like this
from csv import DictReader
with open('names.csv') as f:
dw = DictReader(f, skipinitialspace=True)
fullnames = filter(lambda n: n['First_name'] and n['Last_name'], dw)
for f in fullnames:
print('{}{}'.format(f['First_name'][0], f['Last_name']))
You have headings in your csv so use a DictReader and just filter out those whose with empty first or last names and display the remaining names.
I have a csv file, l__cyc.csv, that contains this:
trip_id, time, O_lat, O_lng, D_lat, D_lng
130041910101,1300,51.5841153671,0.134444590094,51.5718053872,0.134878021928
130041910102,1335,51.5718053872,0.134878021928,51.5786920389,0.180940040247
130041910103,1600,51.5786920389,0.180940040247,51.5841153671,0.134444590094
130043110201,1500,51.5712712038,0.138532882664,51.5334949484,0.130489470325
130043110202,1730,51.5334949484,0.130489470325,51.5712712038,0.138532882664
And I am trying to pull out separate values, using:
with open('./l__cyc.csv', 'rU') as csvfile:
reader = csv.DictReader(csvfile)
origincoords = ['{O_lat},{O_lng}'.format(**row) for row in reader]
with open('./l__cyc.csv', 'rU') as csvfile:
reader = csv.DictReader(csvfile)
trip_id = ['{trip_id}'.format(**row) for row in reader]
with open('./l__cyc.csv', 'rU') as csvfile:
reader = csv.DictReader(csvfile)
destinationcoords = ['{D_lat},{D_lng}'.format(**row) for row in reader]
Where origincoords should be 51.5841153671, 0.134444590094,
trip_id should be 130041910101, and destinationcoords should be
51.5718053872, 0.134878021928.
However, I get a KeyError:
KeyError: 'O_lat'
Is this something simple and there's something fundamental I'm misunderstanding?
You just avoid the space between headers
trip_id,time,O_lat,O_lng,D_lat,D_lng
OR
reader = csv.DictReader(csvfile, skipinitialspace=True)
First things first, you get the key error, because the key does not exist in your dictionary.
Next, I would advise against running through the file 3 times, when you can do it a single time!
For me it worked, when I added the fieldnames to the reader.
import csv
from cStringIO import StringIO
src = """trip_id, time, O_lat, O_lng, D_lat, D_lng
130041910101,1300,51.5841153671,0.134444590094,51.5718053872,0.134878021928
130041910102,1335,51.5718053872,0.134878021928,51.5786920389,0.180940040247
130041910103,1600,51.5786920389,0.180940040247,51.5841153671,0.134444590094
130043110201,1500,51.5712712038,0.138532882664,51.5334949484,0.130489470325
130043110202,1730,51.5334949484,0.130489470325,51.5712712038,0.138532882664
"""
f = StringIO(src)
# determine the fieldnames
fieldnames= "trip_id,time,O_lat,O_lng,D_lat,D_lng".split(",")
# read the file
reader = csv.DictReader(f, fieldnames=fieldnames)
# storage
origincoords = []
trip_id = []
destinationcoords = []
# iterate the rows
for row in reader:
origincoords.append('{O_lat},{O_lng}'.format(**row))
trip_id.append('{trip_id}'.format(**row))
destinationcoords.append('{D_lat},{D_lng}'.format(**row))
# pop the header off the list
origincoords.pop(0)
trip_id.pop(0)
destinationcoords.pop(0)
# show the result
print origincoords
print trip_id
print destinationcoords
I don't really know what you are trying to achieve there, but I'm sure there is a better way of doing it!