如何在熊猫数据帧中生成Alpha-numaric固定长度列

Question

I am trying to create a alpha-numeric(Incremental value) column with fixed length on the basis of one existing column("Number").

I have a below data-frame with me:

Number Space Student
    1      MG    A
    2      FE    B
    3      GD    C
    4      MK    D
    5      OK    E
    6      OO    F
    7      PP    G
    8      QW    H
    9      WE    I
    10     ZA    J
    11     ZQ    K
    ...
    100    ZU    X
    101    ZX    Y
    102    ZB    Z

I need below output (expected output):

Number Space Student NUM4
    1      MG    A   P001
    2      FE    B   P002   
    3      GD    C   P003
    4      MK    D   P004
    5      OK    E   P005
    6      OO    F   P006
    7      PP    G   P007
    8      QW    H   P008
    9      WE    I   P009
    10     ZA    J   P010
    11     ZQ    K   P011
    ...
    100    ZU    X   P100
    101    ZX    Y   P101
    102    ZB    Z   P102

In the above output I want to generate New column(NUM4) on the basis of "Number" column but length of new column must be 4.(Alphabet in new column will remain same)

df['NUM4'] = 'P00' + df['Number']

I am not sure how to introduce a column with fix length which dynamically change as per the "Number" column length. could you please help on this?

Thanks.

Answer 1

Use str.zfill as:

df['NUM4'] = 'P'+df['Number'].astype(str).str.zfill(3)

print(df)
    Number Space Student  NUM4
0        1    MG       A  P001
1        2    FE       B  P002
2        3    GD       C  P003
3        4    MK       D  P004
4        5    OK       E  P005
5        6    OO       F  P006
6        7    PP       G  P007
7        8    QW       H  P008
8        9    WE       I  P009
9       10    ZA       J  P010
10      11    ZQ       K  P011

Answer 2

熊猫的方式来做到这一点：

df['NUM4'] = df.apply(lambda x: f'P{x.Number:03}', axis=1)

Answer 3

The simplest way I can think of is to use f-strings:

df['NUM4'] = df.Number.apply(lambda x: f'P{x:03}')