Source csv:
column a, column b, 2021-01-09, column d
column a, column b, 2021-01-10, column d
column a, column b, 2021-01-11, column d
Desired output:
09/01/2021, column a, column b, column d
10/01/2021, column a, column b, column d
11/01/2021, column a, column b, column d
What is the best method to achieve this, pythonically?
Thanks in advance!
Assuming your row from the csv is like
row = ["column a", "column b", "2021-01-09", "column d"]
you can do something like
import datetime
row.sort()
row[0] = datetime.datetime.strptime(row[0], '%Y-%m-%d').strftime('%d/%m/%y')
gives row as
>>> row
['09/01/21', 'column a', 'column b', 'column d']
One way with pandas to achieve that as you already have answer's using csv.DictWriter
import pandas as pd
df = pd.read_csv('source.csv',names=["ColA", "ColB", "Date", "ColD"])
df['Date'] = pd.to_datetime(df['Date'].str.strip(), format='%Y-%m-%d').dt.strftime('%d/%m/%Y')
new_df = df[['Date', 'ColA', 'ColB', 'ColD']]
print(new_df)
Output:
Date ColA ColB ColD
0 09/01/2021 column a column b column d
1 10/01/2021 column a column b column d
2 11/01/2021 column a column b column d
Reordering, as per:
Python - re-ordering columns in a csv
import csv
with open('file.csv', 'r') as infile, open('reordered.csv', 'a') as outfile:
fieldnames = ['column c', 'column a', 'column b', 'column d']
writer = csv.DictWriter(outfile, fieldnames=fieldnames)
writer.writeheader()
for row in csv.DictReader(infile):
writer.writerow(row)
Adding dates:
In python how to change date format in a csv?
import datetime
with open("reordered.csv", 'r') as csvfile, open('file.csv', 'w') as temp_file:
for line in csvfile.readlines():
# Fetch all dates in the csv
dates = line.split(',')
# Extract date, month and year
yr, mon, dt = dates[0].split('-')
# Convert the second date and replace
dates[0] = datetime.datetime.strptime(dates[0], '%y-%b-%d').strftime('%d/%b/%Y')
# Write date to temp file
temp_file.write(','.join(dates))