在熊猫数据框中将一列拆分为具有特定名称的多列

Question

I have following dataframe:

pri    sec
TOM    AB,CD,EF
JACK   XY,YZ
HARRY  FG
NICK   KY,NY,SD,EF,FR

I need following output with column names as following(based on how many , separated fields exists in column 'sec'):

pri    sec             sec0  sec1  sec2  sec3 sec4
TOM    AB,CD,EF        AB    CD    EF    NaN  NaN
JACK   XY,YZ           XY    YZ    NaN   NaN  NaN
HARRY  FG              FG    NaN   NaN   NaN  NaN
NICK   KY,NY,SD,EF,FR  KY    NY    SD    EF   ER

Can I get any suggestions?

Answer 1

Use join + split + add_prefix :

df = df.join(df['sec'].str.split(',', expand=True).add_prefix('sec'))
print (df)
     pri             sec sec0  sec1  sec2  sec3  sec4
0    TOM        AB,CD,EF   AB    CD    EF  None  None
1   JACK           XY,YZ   XY    YZ  None  None  None
2  HARRY              FG   FG  None  None  None  None
3   NICK  KY,NY,SD,EF,FR   KY    NY    SD    EF    FR

And if need NaN s add fillna :

df = df.join(df['sec'].str.split(',', expand=True).add_prefix('sec').fillna(np.nan))
print (df)
     pri             sec sec0 sec1 sec2 sec3 sec4
0    TOM        AB,CD,EF   AB   CD   EF  NaN  NaN
1   JACK           XY,YZ   XY   YZ  NaN  NaN  NaN
2  HARRY              FG   FG  NaN  NaN  NaN  NaN
3   NICK  KY,NY,SD,EF,FR   KY   NY   SD   EF   FR

Answer 2

Try following code (explanations as comments). It finds max length of items in "sec" column and creates names accordingly:

maxlen = max(list(map(lambda x: len(x.split(",")) ,df.sec))) # find max length in 'sec' column
cols = ["sec"+str(x)   for x in range(maxlen)]      # create new column names 
datalist = list(map(lambda x: x.split(","), df.sec)) # create list from entries in "sec" 
newdf = pd.DataFrame(data=datalist, columns=cols)   # create dataframe of new columns
newdf = pd.concat([df, newdf], axis=1)              # add it to original dataframe
print(newdf)

Output:

     pri             sec sec0  sec1  sec2  sec3  sec4
0    TOM        AB,CD,EF   AB    CD    EF  None  None
1   JACK           XY,YZ   XY    YZ  None  None  None
2  HARRY              FG   FG  None  None  None  None
3   NICK  KY,NY,SD,EF,FR   KY    NY    SD    EF    FR