Error when merging pandas df. TypeError: (“object of type 'float' has no len()”, 'occurred at index D')

Question

The code below effectively merges all values in a pandas df row before any 4 letter string . This only applies to rows directly underneath X in Col A .

df = pd.DataFrame({
    'A' : ['X','Foo','No','','X','Big','No'],           
    'B' : ['','Bar','Merge','','','Cat','Merge'],
    'C' : ['','Fubu','XXXX','','','BgCt','YYYY'],                  
    })

maskX = df.iloc[:,0].apply(lambda x: x=='X')
maskX.index += 1
maskX = pd.concat([pd.Series([False]), maskX])
maskX = maskX.drop(len(maskX)-1)
mask = (df.iloc[:, 1:].applymap(len) == 4).cumsum(1) == 0

for i,v in maskX.items():
    mask.iloc[i,:] = mask.iloc[i,:].apply(lambda x: x and v)

df.A[maskX] = df.A + df.iloc[:, 1:][mask].fillna('').apply(lambda x: x.sum(), 1)
df.iloc[:, 1:] = df.iloc[:, 1:][~mask].fillna('')

This works fine unless there's values other than strings in the df. So if include floats or integers it returns an error to that Column. eg

df = pd.DataFrame({
    'A' : ['X','Foo','No','','X','Big','No'],           
    'B' : ['','Bar','Merge','','','Cat','Merge'],
    'C' : ['','Fubu','XXXX','','','BgCt','YYYY'],
    'D' : ['','',1.0,2.0,3.0,'',''],                   
    })

TypeError: ("object of type 'float' has no len()", 'occurred at index D')

I'm not quite sure why because the merge only occurs to the row beneath X in Col A . None of which contains floats ?

Answer 1

applymap applies the function len to each element of the dataframe. Since floating-point numbers do not have length, the function cannot be applied to them. If you still want to know their "length," convert them to strings:

df.iloc[:, 1:].astype(str).applymap(len)

However, be advised that the function str is not guaranteed to produce a particular string representation of a float. For example, len(str(5.0000)) is 3, not 6, as you might expect.