Using lambda inside loop for iterating over columns

Question

I have a df that has the following structure:

ID | M | C1 | C2 | C3  
tt | 23| 23 | 563| 234    
rt | 13| 3  | 32 | 67  
cf | 78| 67 | 90 | 90  
di | 45| 12 | 112| 34

I want to iterate over columns and create additional columns as a result of the next operations:

additional_column1 = M+1+C1
additional_column2 = additional_column1+1+C2
additional_column3 = additional_column2+1+C3

So that the resulted DF will look like this:

ID | M | C1 | C2 | C3 | AC1 | AC2 | AD3 
tt | 23| 23 | 563| 234|  47 | 611 | 846

I created a for loop, but instead of numbers it fills columns with at 0x7f6e81e2c5e0>

The loop looks as follows:

for c in np.arange(start=1, stop=len(df.columns[1:])+1, step=1):
    df['AC'+str(c)] = lambda c: df.columns[c-1].add(0).sub(df.iloc[:, c])

Need clue, where I did a mistake. Thanks in advance.

why are you using lambda at all?

juanpa.arrivillaga
– juanpa.arrivillaga

2020-04-09 17:24:58 +00:00
Commented Apr 9, 2020 at 17:24 — juanpa.arrivillaga
– juanpa.arrivillaga, Commented Apr 9, 2020 at 17:24

Bruno Mello · Accepted Answer · 2020-04-09 17:13:13Z

1

IIUC:

for c in np.arange(start=1, stop=len(df.columns[1:])+1, step=1):
    df['AC'+str(c)] = df.iloc[: , c-1].add(0).sub(df.iloc[:, c])

answered Apr 9, 2020 at 17:13

Bruno Mello

4,6781 gold badge16 silver badges46 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

anky Over a year ago

i am not able to generate the expected output for the first column using this, what am I missing?

anky · Accepted Answer · 2020-04-09 17:21:36Z

0

You can also try df.cumsum() on axis=1 and add the 1 as a range.

# df = df.set_index('ID') if ID is not an index
out = df.assign(**df.cumsum(axis=1).add(range(df.shape[1])).iloc[:,1:].add_prefix('A'))

     M  C1   C2   C3  AC1  AC2  AC3
ID                                 
tt  23  23  563  234   47  611  846
rt  13   3   32   67   17   50  118
cf  78  67   90   90  146  237  328
di  45  12  112   34   58  171  206

answered Apr 9, 2020 at 17:21

anky

75.3k11 gold badges46 silver badges76 bronze badges

Comments

orr · Accepted Answer · 2020-04-09 17:25:48Z

0

You can simply do this: (worked for me)

df = pd.DataFrame(data=[[23,23,563,234],[13,3,32,67],[78,67,90,90],[45,12,112,34]], columns=['M','C1','C2','C3'])

columns = df.columns

last_col = None
for i, col in enumerate(columns):
    if last_col is None:
        last_col = col
        continue
    df['AC' + str(i)] = df[last_col] + 1 + df[col]
    last_col = 'AC' + str(i)

answered Apr 9, 2020 at 17:25

orr

15914 bronze badges

Collectives™ on Stack Overflow

Using lambda inside loop for iterating over columns

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related