[英]Adding new column to CSV in Python
I would like to add a new column to my CSV in Python. 我想在Python中为CSV添加新列。 I understand that in Python I will have to run the CSV and rewrite a new one as an output to add a column.
我了解在Python中,我将必须运行CSV并重写一个新的CSV作为输出以添加列。
I want to run though each UserID and assign a UniqueID to it. 我想通过每个用户ID运行并为其分配一个唯一ID。
This is my input : 这是我的输入 :
UserID,name
a,alice
a,alice
b,ben
c,calvin
c,calvin
c,calvin
This is my desired output : 这是我想要的输出 :
UniqueID,UserID,name
1,a,alice
1,a,alice
2,b,ben
3,c,calvin
3,c,calvin
3,c,calvin
I am new to Python and was wondering if anyone can show me how this can be done. 我刚接触Python,想知道是否有人可以向我展示如何做到这一点。 Thanks.
谢谢。
Here is my code so far:
import csv
import operator
temp_index = 0
with open("./coordinates.csv") as all_coordinates_csv:
coordinate_reader = csv.reader(all_coordinates_csv, delimiter=",")
sort = sorted(coordinate_reader,key=operator.itemgetter(0))
with open("./sorteduserid.csv","wb") as sorteduser_csv:
csv_writer = csv.writer(sorteduser_csv,delimiter=",")
csv_writer.writerows(sort)
Take a try with my code: 试试看我的代码:
import csv
import uuid
is_first = True
with open('test.csv', newline='') as input_file:
with open('output.csv', 'w', newline='') as output_file:
writer = csv.writer(output_file)
reader = csv.reader(input_file)
for row in reader:
if is_first:
row.insert(0, 'UniqueID')
is_first = False
else:
row.insert(0, str(uuid.uuid4()))
writer.writerow(row)
This solution is based on your own attempt: 此解决方案基于您自己的尝试:
import csv
import operator
from itertools import groupby
with open("./coordinates.csv") as all_coordinates_csv:
coordinate_reader = csv.reader(all_coordinates_csv, delimiter=",")
sort = sorted(coordinate_reader,key=operator.itemgetter(0))
grouped = []
for key, group in groupby(sort, lambda x: x[0]):
grouped.append(list(group))
data_out = [];
data_out.append(['Unique_ID', (grouped[0])[0][0], (grouped[0])[0][1]])
user_id = 1
for group in grouped[1:]:
for user in group:
data_out.append([user_id,user[0],user[1]])
user_id += 1
with open("./sorteduserid.csv","wb") as sorteduser_csv:
csv_writer = csv.writer(sorteduser_csv,delimiter=",")
csv_writer.writerows(data_out)
After you sort your input the program uses groupby
to group the values by UserID in sort
. 在对输入进行排序后,程序将使用
groupby
来按sort
的UserID对值进行分组。 It then uses those grouped values in the loops to assign a unique ID to each UserID. 然后,它将在循环中使用这些分组的值为每个UserID分配一个唯一的ID。 Before the loops, it extends the header with
User_ID
entry. 在循环之前,它将使用
User_ID
条目扩展标题。
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