Develop Reference

Print only second row

I have CSV File named as names.csv:
F_Name | L_Name
Sashi | Thakur
Rup | Chand
Nirmal | Kumar
Trying to print only L_Name:
import csv
with open('names.csv', newline='') as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
#print(row['first_name'], row['last_name'])
print(row[1])
Gave me:
KeyError: 2
Thankyou

As per your latest comment you want to print last name which are in second column(index 1)
If fieldnames are not present then you should not use DictReader as it will take whatever in first row as key
import csv
with open('cs.csv', newline='') as csvfile:
reader = csv.reader(csvfile)
for row in reader:
print(row[1])
#--------------------------------------------------
# fieldnames are present
import csv
with open('cs.csv', newline='') as csvfile:
reader = csv.DictReader(csvfile)
#print(reader.fieldnames)
look_for = reader.fieldnames[1] #since L_name is at index 1
for row in reader:
print(row[look_for])
'''
csv file contents
F_Name,L_Name
Sherlock,Holmes
Bruce,Wayne
OrderedDict([('F_Name', 'Sherlock'), ('L_Name', 'Holmes')])
Holmes
OrderedDict([('F_Name', 'Bruce'), ('L_Name', 'Wayne')])
Wayne
['F_Name', 'L_Name']
Holmes
Wayne
'''

Indices start at 0! So to get the the second column you have to access row[1]

You can user the argument fieldnames to give columns key names, then print each column by the key name.
import csv with open('names.csv', newline='') as csvfile:
reader = csv.DictReader(csvfile, fieldnames=['fname', 'lname'])
for row in reader:
print(row['lname'])
reference: https://docs.python.org/2/library/csv.html

CSV created with Python is blank

This question was answered/resolved in the comments section.
I am a noob to Python and I wrote the code below thinking it would copy all the rows with "NY" as the state in the state field/column to a new csv file called "Output.csv".
import csv
f = open(r'C:\Users..\input.csv', 'r')
reader = csv.DictReader(f, delimiter=',')
output = open("C:...\Output.csv",'w')
fieldnames = ['firstScan', 'FinalScan', 'City', 'State', 'cld', 'daydiff']
writer = csv.DictWriter(output, fieldnames=fieldnames, delimiter=',')
for row in reader:
if row['State'] == 'NY':
writer.writerow(row)
Everything runs fine but the output csv is completely blank. The first tab is named "Output" but the sheet is blank. If I have it output to txt, that is blank as well. Any suggestions?

Try this instead:
import csv
with open('C:/Users/felasniper/Desktop/input.csv') as f:
reader = csv.DictReader(f, delimiter=',')
output = open("C:/Users/felasniper/Desktop/Output.csv", 'w')
fieldnames = ['firstScan', 'FinalScan', 'City', 'State', 'cld', 'daydiff']
writer = csv.DictWriter(output, fieldnames=fieldnames, delimiter=',')
for row in reader:
if row['State'] == 'NY':
writer.writerow(row)

Python CSV Row Loop

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)

(Simple Python) CSV input to usernames

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.

Adding a column in csv using python

I have hundreds of .csv files with 40 rows and 34 columns each. I want to add a column at position 26 and column 26-34 should shift to make space for the new one. First row of the file is empty and second row has the titles and rest have the values. The new column should have a title in row two and rest of the rows can be zero.
Please help me with this code in python.
import csv
infilename = r'C:\Users\Sulabh Kumra\Desktop\input.csv'
outfilename = r'C:\Users\Sulabh Kumra\Desktop\output.csv'
with open(infilename, 'rb') as fp_in, open(outfilename, 'wb') as fp_out:
reader = csv.reader(fp_in, delimiter=",")
headers = next(reader) # read first row
writer = csv.writer(fp_out, delimiter=",")
writer.writerow(headers)
for row in reader:
row.append(row[2])
writer.writerow(row)

Inserting into a python list is pretty easy: some_list[2:2] = ['stuff','to','insert']
So your code would look like the following:
import csv
infilename = r'C:\Users\Sulabh Kumra\Desktop\input.csv'
outfilename = r'C:\Users\Sulabh Kumra\Desktop\output.csv'
with open(infilename, 'rb') as fp_in, open(outfilename, 'wb') as fp_out:
reader = csv.reader(fp_in, delimiter=",")
writer = csv.writer(fp_out, delimiter=",")
blank_line = next(reader)
writer.writerow(blank_line)
headers = next(reader) # read title row
headers[26:26] = ['New Label']
writer.writerow(headers)
for row in reader:
row[26:26] = [0]
writer.writerow(row)