Python Pandas Add empty column in the middle of a dataframe

Question

I am trying to add an empty column after the 3ed column on my data frame that contains 5 columns. Example:

Fname,Lname,city,state,zip

mike,smith,new york,ny,11101

This is what I have and below I am going to show what I want it to look like.

Fname,Lname,new column,city,state,zip

mike,smith,,new york,ny,11101

I dont want to populate that column with data all I want to do is add the extra column in the header and that data will have the blank column aka ',,'. Ive seen examples where a new column is added to the end of a data frame but not at a specific placement.

Add the column then use reindex with axis=1 to order columns the way you want. — Scott Boston
– Scott Boston, Commented May 2, 2019 at 17:44
@ScottBoston what would I use to write this to a new csv file named 'new.csv' — Klaidi Ziaj
– Klaidi Ziaj, Commented May 2, 2019 at 18:09

nassim · Accepted Answer · 2019-05-02 17:49:39Z

18

you should use

df.insert(loc, column, value)

with loc being the index and column the column name and value it's value

for an empty column

df.insert(loc=2, column='new col', value=['' for i in range(df.shape[0])])

answered May 2, 2019 at 17:49

nassim

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10 Comments

Klaidi Ziaj Over a year ago

what would I use to write this to a new csv file named 'new.csv'

nassim Over a year ago

df.to_csv('new.csv',index=False)

Klaidi Ziaj Over a year ago

That is exactly what I have but for some reason its not putting out another file.

Klaidi Ziaj Over a year ago

import pandas as pd df = pd.read_csv (r'C:\Users\kziaj\Desktop\Python Test\new.csv') df.insert(loc=1, column='avalue', value=[',' for i in range(df.shape[0])]) df.to_csv('new1.csv',index=False) #Print in new file

Klaidi Ziaj Over a year ago

No im not im using visual studio code off my desktop

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Scott Boston · Accepted Answer · 2019-05-02 17:48:49Z

3

Use reindex or column filtering

df = pd.DataFrame(np.arange(50).reshape(10,-1), columns=[*'ABCDE'])

df['z']= np.nan

df[['A','z','B','C','D','E']]

OR

df.reindex(['A','z','B','C','D','E'], axis=1)

Output:

    A   z   B   C   D   E
0   0 NaN   1   2   3   4
1   5 NaN   6   7   8   9
2  10 NaN  11  12  13  14
3  15 NaN  16  17  18  19
4  20 NaN  21  22  23  24
5  25 NaN  26  27  28  29
6  30 NaN  31  32  33  34
7  35 NaN  36  37  38  39
8  40 NaN  41  42  43  44
9  45 NaN  46  47  48  49

answered May 2, 2019 at 17:48

Scott Boston

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3 Comments

Klaidi Ziaj Over a year ago

what would I use to write this to a new csv file named 'new.csv'

Scott Boston Over a year ago

to_csv('new.csv') you might want to fillna('') and/or index=False.

Klaidi Ziaj Over a year ago

would you be able to script this for some reason its not creating a new file

singh_ap · Accepted Answer · 2019-05-02 18:03:13Z

2

You can simply go for df.insert()

import pandas as pd
data = {'Fname': ['mike'], 
        'Lname': ['smith'], 
        'city': ['new york'],
        'state': ['ny'],
        'zip': [11101]}
df = pd.DataFrame(data) 
df.insert(1, "Address", '', True)
print(df)

Output:

  Fname Address  Lname      city state    zip
0  mike          smith  new york    ny  11101

answered May 2, 2019 at 18:03

singh_ap

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2 Comments

Klaidi Ziaj Over a year ago

what would I use to write this to a new csv file named 'new.csv'

singh_ap Over a year ago

for saving the df to a new file "new.csv", use df.to_csv(filename)

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