CODEWITHSUNDEEP
pythonpandas
Jorge Gill
Jorge Gill

Reputation: 315

Using apply method to modify a DataFrame

Lets say I have the following DataFrame:

X,Y,Z
a,b,c
d,e,m
h,i,m
k,l,m

I want to be able to use the .apply method to call a function on this dataframe, so like df.apply(modFunc()) to be able to change all the m values in column Z to o, so the result is

X,Y,Z
a,b,c
d,e,o
h,i,o
k,l,o

This is my try, so far I haven't found the solution:

def replaceFunc():
    df['X'] = df.X.str.replace("m", "o")

df.apply(replaceFunc())

Doing this I get the following error:

TypeError: ("'NoneType' object is not callable", 'occurred at index STATION')

Upvotes: 2

Views: 1049

Answers (1)

jezrael
jezrael

Reputation: 862406

If want use apply is possible add axis=1 for processes by rows of DataFrames:

def replaceFunc(x):
    x['Z'] = x.Z.replace("m", "o")
    return x

df1 = df.apply(replaceFunc, axis=1)

Your solution should be changed by DataFrame.pipe for processing DataFrame in function:

def replaceFunc(x):
    x['Z'] = x.Z.str.replace("m", "o")
    return x

df1 = df.pipe(replaceFunc)

Alternative:

df1 = replaceFunc(df)

Upvotes: 1

Related Questions