The header line in my csv file is:
Number,Name,Type,Manufacturer,Material,Process,Thickness (mil),Weight (oz),Dk,Orientation,Pullback distance (mil),Description
I can open it and read the line, with no problems:
infile = open('CS_Data/_AD_LayersTest.csv','r')
csv_reader = csv.reader(infile, delimiter=',')
for row in csv_reader:
But I want to find out what the item number is for the "Dk".
The problem is that not only can the items be in any order as decided by the user in a different application. There can also be up to 25 items in the line.
How do I quickly determine what item is "Dk" so I can write Dk = (row[i]) for it and extract it for all the data after the header.
I have tried this below on each of the potential 25 items and it works, but it seems like a waste of time, energy and my ocd.
while True:
try:
if (row[0]) == "Dk":
DkColumn = 0
break
elif (row[1]) == "Dk":
DkColumn = 1
break
...
elif (row[24]) == "Dk":
DkColumn = 24
break
else:
f.write('Stackup needs a "Dk" column.')
break
except:
print ("Exception occurred")
break
Can't you get the index of the column (using list.index()) that has the value Dk in it? Something like:
infile = open('CS_Data/_AD_LayersTest.csv','r')
csv_reader = csv.reader(infile, delimiter=',')
# Store the header
headers = next(csv_reader, None)
# Get the index of the 'Dk' column
dkColumnIndex = header.index('Dk')
for row in csv_reader:
# Access values that belong to the 'Dk' column
rowDkValue = row[dkColumnIndex]
print(rowDkValue)
In the code above, we store the first line of the CSV in as a list in headers. We then search the list to find the index of the item that has the value of 'Dk'. That will be the column index.
Once we have that column index, we can then use it in each row to access the particular index, which will correspond to the column which Dk is the header of.
Use pandas library to save your order and have access to each column by typing:
row["column_name"]
import pandas as pd
dataframe = pd.read_csv(
"",
cols=["Number","Name","Type" ....])
for index, row in df.iterrows():
# do something
If I understand your question correctly, and you're not interested in using pandas (as suggested by Mikey - you sohuld really consider his suggestion, however), you should be able to do something like the following:
with open('CS_Data/_AD_LayersTest.csv','r') as infile:
csv_reader = csv.reader(infile, delimiter=',')
header = next(csv_reader)
col_map = {col_name: idx for idx, col_name in enumerate(header)}
for row in csv_reader:
row_dk = row[col_map['Dk']]
One solution would be to use pandas.
import pandas as pd
df=pd.read_csv('CS_Data/_AD_LayersTest.csv')
Now you can access 'Dk' easily as long as the file is read correctly.
dk=df['Dk']
and you can access individual values of dk like
for i in range(0,10):
temp_var=df.loc('Dk',i)
or however you want to access those indexes.
Related
I want to insert data into a dataframe like the image below with only CSV module in Python.
Is there any way to split rows this way?
You should think in terms of what is a csv file rather than the python csv module.
CSV files are nothing more than text representations of flat tables, therefore your sub-categories and sub-totals require separate rows.
If you want to create an object with a list of <sub-category, sub-total> pairs you have to parse the rows accordingly.
First you read a category and a total frequency and create the new category object, then until category stays the same you can add <sub-category, sub-total> pairs to its sub-categories list.
With the assumptions that category is unique and that there is an header row, you could try something like this:
import csv
with open('cats.csv', mode='r') as csv_file:
fieldnames = ['category', 'total', 'sub-category', 'sub-total']
csv_reader = csv.DictReader(csv_file, fieldnames=fieldnames)
lastCat = ""
nextCat = ""
row = next(csv_reader) # I'm skipping the first line
row = next(csv_reader, '')
while True:
if row == '':
break
nextCat = row['category']
lastCat = nextCat
newCategory = Category.fromCSV(row) # This is just an example
while nextCat == lastCat:
newCategory.addData(row)
row = next(csv_reader, '')
if row == '':
break
nextCat = row['category']
I didn't test my code, so I don't recommend you to use as something more than a suggestion
CSV file:
Acct,phn_1,phn_2,phn_3,Name,Consent,zipcode
1234,45678,78906,,abc,NCN,10010
3456,48678,,78976,def,NNC,10010
Problem:
Based on consent value which is for each of the phones (in 1st row: 1st N is phn_1, C for phn_2 and so on) I need to retain only that phn column and move the remaining columns to the end of the file.
The below is what I have. My approach isn't that great is what I feel. I'm trying to get the id of the individual Ns and Cs, get the id and map it with the phone (but I'm unable to iterate through the phn headers and compare the id's of the Ns and Cs)
with open('file.csv', 'rU') as infile:
reader = csv.DictReader(infile) data = {} for row in reader:
for header, value in row.items():
data.setdefault(header, list()).append(value) # print(data)
Consent = data['Consent']
for i in range(len(Consent)):
# print(list(Consent[i]))
for idx, val in enumerate(list(Consent[i])):
# print(idx, val)
if val == 'C':
#print("C")
print(idx)
else:
print("N")
Could someone provide me with the solution for this?
Please Note: Do not want the solution to be by using pandas.
You’ll find my answer in the comments of the code below.
import csv
def parse_csv(file_name):
""" """
# Prepare the output. Note that all rows of a CSV file must have the same structure.
# So it is actually not possible to put the phone numbers with no consent at the end
# of the file, but what you can do is to put them at the end of the row.
# To ensure that the structure is the same on all rows, you need to put all phone numbers
# at the end of the row. That means the phone number with consent is duplicated, and that
# is not very efficient.
# I chose to put the result in a string, but you can use other types.
output = "Acct,phn,Name,Consent,zipcode,phn_1,phn_2,phn_3\n"
with open(file_name, "r") as csvfile:
reader = csv.DictReader(csvfile)
for row in reader:
# Search the letter “C” in “Consent” and get the position of the first match.
# Add one to the result because the “phn_×” keys are 1-based and not 0-based.
first_c_pos = row["Consent"].find("C") + 1
# If there is no “C”, then the “phn” key is empty.
if first_c_pos == 0:
row["phn"] = ""
# If there is at least one “C”, create a key string that will take the values
# phn_1, phn_2 or phn_3.
else:
key = f"phn_{first_c_pos}"
row["phn"] = row[key]
# Add the current row to the result string.
output += ",".join([
row["Acct"], row["phn"], row["Name"], row["Consent"],
row["zipcode"], row["phn_1"], row["phn_2"], row["phn_3"]
])
output += "\n"
# Return the string.
return(output)
if __name__ == "__main__":
output = parse_csv("file.csv")
print(output)
I have 2 stock lists (New and Old). How can I compare it to see what items have been added and what had been removed (happy to add them to 2 different files added and removed)?
so far I have tired along the lines of looking row by row.
import csv
new = "new.csv"
old = "old.csv"
add_file = "add.csv"
remove_file = "remove.csv"
with open(new,encoding="utf8") as new_read, open(old,encoding="utf8") as old_read:
new_reader = csv.DictReader(new_read)
old_reader = csv.DictReader(old_read)
for new_row in new_reader :
for old_row in old_reader:
if old_row["STOCK CODE"] == new_row["STOCK CODE"]:
print("found")
This works for 1 item. if I add an *else: * it just keeps printing that until its found. So it's not an accurate way of comparing the files.
I have 5k worth of rows.
There must be a better way to add the differences to the 2 different files and keep the same data structure at the same time ?
N.B i have tired this link Python : Compare two csv files and print out differences
2 minor issues:
1. the data structure is not kept
2. there is not reference to the change of location
You could just read the data into memory and then compare.
I used sets for the codes in this example for faster lookup.
import csv
def get_csv_data(file_name):
data = []
codes = set()
with open(file_name, encoding="utf8") as csv_file:
reader = csv.DictReader(csv_file)
for row in reader:
data.append(row)
codes.add(row['STOCK CODE'])
return data, codes
def write_csv(file_name, data, codes):
with open(file_name, 'w', encoding="utf8", newline='') as csv_file:
headers = list(data[0].keys())
writer = csv.DictWriter(csv_file, fieldnames=headers)
writer.writeheader()
for row in data:
if row['STOCK CODE'] not in codes:
writer.writerow(row)
new_data, new_codes = get_csv_data('new.csv')
old_data, old_codes = get_csv_data('old.csv')
write_csv('add.csv', new_data, old_codes)
write_csv('remove.csv', old_data, new_codes)
I am trying to read some data files '.txt' and some of them contain strange random characters and even extra columns in random rows, like in the following example, where the second row is an example of a right row:
CTD 10/07/30 05:17:14.41 CTD 24.7813, 0.15752, 1.168, 0.7954, 1497.¸ 23.4848, 0.63042, 1.047, 3.5468, 1496.542
CTD 10/07/30 05:17:14.47 CTD 23.4846, 0.62156, 1.063, 3.4935, 1496.482
I read the description of np.loadtxt and I have not found a solution for my problem. Is there a systematic way to skip rows like these?
The code that I use to read the files is:
#Function to read a datafile
def Read(filename):
#Change delimiters for spaces
s = open(filename).read().replace(':',' ')
s = s.replace(',',' ')
s = s.replace('/',' ')
#Take the columns that we need
data=np.loadtxt(StringIO(s),usecols=(4,5,6,8,9,10,11,12))
return data
This works without using csv like the other answer and just reads line by line checking if it is ascii
data = []
def isascii(s):
return len(s) == len(s.encode())
with open("test.txt", "r") as fil:
for line in fil:
res = map(isascii, line)
if all(res):
data.append(line)
print(data)
You could use the csv module to read the file one line at a time and apply your desired filter.
import csv
def isascii(s):
len(s) == len(s.encode())
with open('file.csv') as csvfile:
csvreader = csv.reader(csvfile)
for row in csvreader:
if len(row)==expected_length and all((isascii(x) for x in row)):
'write row onto numpy array'
I got the ascii check from this thread
How to check if a string in Python is in ASCII?
Trying to sum a column in a csv file that has a header row at the top. I'm trying to use this for loop but it's just return zero. Any thoughts?
CSVFile = open('Data103.csv')
CSVReader = csv.reader(CSVFile) #you don't pass a file name directly to csv.reader
CSVDataList = list(CSVReader) #stores the csv file as a list of lists
print(CSVDataList[0][16])
total = 0
for row in CSVReader:
if CSVReader.line_num == 1:
continue
total += int(row[16])
print (total)
Here is what the data sample looks like in txt:
Value,Value,Value, "15,500.05", 00.00, 00.00
So the items are deliminted by , except in the case where they need an escape then it's "". It's a pretty standard file with a header row and about 1k lines of data across 18 columns.
You might want to use Pandas.
import pandas as pd
df = pd.read_csv('/path/to/file.csv')
column_sum = df['column_name'].sum()
It seems that you've over-indented the line that does the sum. It should be like this:
for row in CSVReader:
if CSVReader.line_num == 1:
continue
total += int(row[16])
Otherwise you'll only sum the values for the first row, which is exactly the one you want to skip.
EDIT:
Since you said the previous change doesn't work, I'd suggest working with the excellent Python lib called rows.
With the following CSV (fruits.csv):
id,name,amount
1,apple,3
2,banana,6
3,pineapple,2
4,lemon,5
You can access columns directly by their name instead of their index:
import rows
data = rows.import_from_csv('fruits.csv')
for fruit_data in data:
print(fruit_data.name, fruit_data.amount)
# output:
# apple 3
# banana 6
# pineapple 2
# lemon 5
NEW EDIT:
After you've provided the data, I believe in your case you could do something like:
import rows
data = rows.import_from_csv('Data103.csv')
print(data.field_names[16]) # prints the field name
total = 0
for row in data:
value = row.<column_name>
value = value.replace(',', '') # remove commas
total += float(value)
print (total)