CODEWITHSUNDEEP
pythoncsv
Daniel Hutchinson
Daniel Hutchinson

Reputation: 165

Python: write CSV column with loop

Using Python, I'd like to create a loop to write text in a CSV file when a row contains text.

The original CSV format is:

user_id,    text
0,  
1,  
2,  
3,  sample text
4,  sample text

I'm seeking to add another column "text_number" that will insert the string "text_x", with x representing the number of texts in the column. I'd like to iterate this and increase the string's value by +1 for each new text. The final product would look like:

user_id,    Text,   text_number
0,      
1,      
2,      
3,  sample text,    text_0
4,  sample text,    text_1

With my working code I can insert the header "text_number", but I'm having difficulty in putting together the loop for text_x.

import csv

output = list()
with open("test.csv") as file:
    csv_reader = csv.reader(file)
    for i, row in enumerate(csv_reader):
        if i == 0:
            output = [row+["text_number"]]
            continue
        # here's where I'm stuck
            
with open("output2.csv", "w", newline="") as file:
    csv_writer = csv.writer(file, delimiter=",")
    for row in output:
        csv_writer.writerow(row)

Any thoughts?

Upvotes: 0

Views: 966

Answers (3)

imxitiz
imxitiz

Reputation: 3987

You can try this:

import csv

output = list()
x=0
with open("test.csv") as file:
    csv_reader = csv.reader(file)
    for i, row in enumerate(csv_reader):
        row[1]=row[1].strip()
        if i == 0:
            row.append("text_number")
        else:
            if row[1]=="":
                row.append(" ")
            else:
                row.append(f"text_{x}")
                x+=1
        output.append(row)            
with open("output2.csv", "w", newline="") as file:
    csv_writer = csv.writer(file, delimiter=",")
    for row in output:
        csv_writer.writerow(row)

I haven't changed anything in your code, which should be changed. I am just adding new element in row in every iteration. And append that every row in output, for making new list of row.

If you are comfortable with pandas then you can try this too:


import pandas as pd

df=pd.read_csv("test.csv")

r=[]
x=0
for i in range(df.shape[0]):
    if df["    text"][i].strip()=="":
        r.append(f" ")
    else:
        r.append(f"text_{x}")
        x+=1

df["text_number"]=r

print(df)
"""
   user_id           text   text_number
0        0                     
1        1                     
2        2                     
3        3    sample text      text_0
4        4    sample text      text_1
"""
pd.to_csv("output2.csv")

Here we are making list for text_number column.

Upvotes: 1

Epsi95
Epsi95

Reputation: 9047

find description in comments

# asuming the file
# user_id,text
# 0,  
# 1,  
# 2,  
# 3,sample text
# 4,sample text
# 5, 
# 6,sample text

# import the library
import pandas as pd
df = pd.read_csv('test.csv').fillna('')

# creating column text_number initializing with ''
df['text_number'] = ''

# getting the index where text is valid
index = df.loc[df['text'].str.strip().astype(bool)].index

# finally creating the column text_number with increment as 0, 1, 2 ...
df.loc[index, 'text_number'] = [f'text_{i}' for i in range(len(index))]

print(df)

# save it to disk
df.to_csv('output2.csv')


#    user_id         text text_number
# 0        0                         
# 1        1                         
# 2        2                         
# 3        3  sample text      text_0
# 4        4  sample text      text_1
# 5        5                         
# 6        6  sample text      text_2

Upvotes: 1

Timus
Timus

Reputation: 11321

You could try the following modification of your first part:

output = list()
with open("test.csv") as file:
    csv_reader = csv.reader(file)
    output.append(next(csv_reader) + ['text_number'])
    text_no = 0
    for row in csv_reader:
        if row[1].strip():
            row.append(f'text_{text_no}')
            text_no += 1
        output.append(row)

Upvotes: 1

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