类型错误：append() 缺少 1 个必需的位置参数：“其他”

Question

I have several dataframes (of the same shape) that I want to append creating one larger data-frame. Tee individual data-frames all have the type:

C-Mastersheet.xlsx   <class 'pandas.core.frame.DataFrame'>
D-Mastersheet.xlsx   <class 'pandas.core.frame.DataFrame'>
L-Mastersheet.xlsx   <class 'pandas.core.frame.DataFrame'>

and look like:

C-Mastersheet.xlsx

   First Name  Last name        Dept  Location  Status      Concat 
0          Jo      Jones    Accounts   Bristol Current     JonesJo
1         Sid      Smith       Sales      Hull     New    SmithSid

D-Mastersheet.xlsx

       First Name  Last name        Dept  Location  Status      Concat 
0            Phil      Evans  Production      Hull Current   EvansPhil
1           Sarah      Heath   Marketing   Bristol Current  HeathSarah
2            Jane       Hill    Accounts   Bristol Current    HillJane
3             Amy     Cooper       Sales      Hull Current   CooperAmy

L-Mastersheet.xlsx

   First Name  Last name        Dept  Location  Status      Concat
0      Marcus      Price  Operations      Hull Current PriceMarcus
1      Andrew       King      Design   Bristol Current  KingAndrew
2        Emma       Lane   Marketing   Bristol Current    LaneEmma
3       Brian       Deen    Accounts   Bristol Current   DeenBrian       
4       Steve      Jacks      Design   Bristol Current  JacksSteve

I am trying to return the output:

  First Name  Last name        Dept  Location   Status      Concat 
 0         Jo      Jones    Accounts   Bristol Current     JonesJo
 1        Sid      Smith       Sales      Hull New        SmithSid
 2       Phil      Evans  Production      Hull Current   EvansPhil
 3      Sarah      Heath   Marketing   Bristol Current  HeathSarah
 4       Jane       Hill    Accounts   Bristol Current    HillJane
 5        Amy     Cooper       Sales      Hull Current   CooperAmy
 6     Marcus      Price  Operations      Hull Current PriceMarcus
 7     Andrew       King      Design   Bristol Current  KingAndrew
 8       Emma       Lane   Marketing   Bristol Current    LaneEmma
 9      Brian       Deen    Accounts   Bristol Current   DeenBrian       
10      Steve      Jacks      Design   Bristol Current  JacksSteve

I am trying to do this using the follwing code whioch loops around a directory:

ConsolidatedData = pd.DataFrame

for i in os.listdir(os.chdir(returnsfolder)):
    if i.endswith(".xlsx"):
        )
        rawFilePath = returnsfolder +'\\'+ i

        DeptReturn = openRawDeptReturn(rawFilePath)

        ConsolidatedData = ConsolidatedData.append(DeptReturn,ignore_index=True)

I am however getting the following type error:

TypeError: append() missing 1 required positional argument: 'other'

I have not come across this before.

Answer 1

This is the problem:

df = pd.DataFrame           # returns class
df = df.append(DeptReturn)  # TypeError: append() missing 1 required positional argument: 'other'

The reason behind the error is the first argument of a method is the class instance. In this case, the class instance is inferred to be DeptReturn and there is no 'other' argument supplied.

What you need is:

df = pd.DataFrame()         # returns class instance
df = df.append(DeptReturn)  # returns instance with method applied

For the first argument we have the class instance df , since the method is being applied on that instance. The second argument is DeptReturn .

See also: What is the purpose of self?