Pandas - Add leading “0” to string values so all values are equal len

Question

I have a column, code_x. I converted it to .astype(str). Some example values are 45362.0, 75345.0, 346157.0, 572575.0. I would like them a

Answer 1

Even I am with @DSM for using zfill. But I think using lamba makes it much cleaner and easy to read.

In [1]: import pandas as pd

In [2]: df = pd.DataFrame([45362.0, 75345.0, 346157.0, 572575.0], columns=['code_x'])

In [3]: df.code_x.apply(lambda x: str(int(x)).zfill(6))
Out[3]: 
0    045362
1    075345
2    346157
3    572575
Name: code_x, dtype: object

Note: We are converting a given value to int before converting to string to get rid of ".0" in results.

Answer 2

You can use the Series.str.rjust method to right justify the string values and use 8 as the length and 0 as fill value. Example -

df3['code_x'] = df3['code_x'].astype(str).str.rjust(8,'0')

Demo -

In [65]: df
Out[65]:
        A
0    blah
1  supbla
2       a

In [69]: df['A'].str.rjust(6,'0')
Out[69]:
0    00blah
1    supbla
2    00000a
Name: A, dtype: object

Answer 3

IIUC, you can use str.zfill which means you wouldn't have to special-case by length:

In [16]: ser
Out[16]: 
0     45362
1     75345
2    346157
3    572575
dtype: float64

In [17]: ser.astype(str).str.zfill(8)
Out[17]: 
0    045362.0
1    075345.0
2    346157.0
3    572575.0
dtype: object