Add new column with vlaue based on other colum starting charchter-CodePudding

using pandas I want to be fill DVZ column with data (data1, data2, etc..) based on starting sting of column DV2 for example if start with 9 will add data1 to DVZ first raw and second if start with 7 will add data2 if start with 7 will be data3 in DVZ

i am trying with dew['DVZ'][dew["DV0"].astype('str').str.startswith("9")] = "Sin" but not able to reach desire result . appreciate if any one can hint me

DV1	DV2	DVZ
9412	941	new data
9434	911	new data
9412	717	new data
3114	311	new data
6314	631	new data
6622	662	new data

here hope result

DV1	DV2	DVZ
9412	941	data1
9434	911	data1
9412	717	data2
3114	311	data3
6314	631	data4
6622	662	data4

CodePudding user response：

IIUC, you can use:

c = df['DV2'].astype(str).str[0]
df['DVZ'] = 'data'   c.ne(c.shift()).cumsum().astype(str)
print(df)

# Output
    DV1  DV2    DVZ
0  9412  941  data1
1  9434  911  data1
2  9412  717  data2
3  3114  311  data3
4  6314  631  data4
5  6622  662  data4

Update

Because DV2 is start with 9 I will add the word data1 when start with 7 I will put date2 with start with 4 I put data3 and so on.

Create a mapping dict:

M = {'9': 'data1', '7': 'data2', '3': 'data3', '6': 'data4'} # and so on
df['DVZ'] = df['DV2'].astype(str).str[0].map(M)
print(df)

# Output
    DV1  DV2    DVZ
0  9412  941  data1
1  9434  911  data1
2  9412  717  data2
3  3114  311  data3
4  6314  631  data4
5  6622  662  data4