使用 pandas 迭代 dataframe 并替换字符

Question

My data frame column named 'Shrinkage' looks like:

-Shrinkage
-($614)
-$0
-$0
-$0
-$0
-$0
-$0
-$0
-($125)
-$320
-$3,779
($2,482)

With the following code, I am trying to perform multiple actions with a for loop and if statement. I would like to iterate through the column and if the object has the character '(' then I want to replace it with the character '-' to make that number negative. As well as finding and replacing the negative numbers, I would like to remove all characters and make the objects into floats to perform math with it.

for i in ['Shrinkage']:
    if df['Shrinkage'] == '(':
        df['Shrinkage'] = df['Shrinkage'].replace({'(': '-'}).astype(float)
        df['Shrinkage'] = df['Shrinkage'].replace({'$': '', ')': '', ',': ''})
    else:
        df['Shrinkage'].replace({'$': '', ',': ''}, regex=True).astype(float)

I am getting a ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

Please understand I am still new to python and haven't got into complex code yet. Some help is needed please.

Answer 1

try this, series.replace and use regex to remove un-wanted characters.

df['Shrinkage'] = df['Shrinkage'].str.replace("\(|\$|\)|,", "")

print(df['Shrinkage'].astype(float))

output,

0     -614.0
1       -0.0
2       -0.0
3       -0.0
4       -0.0
5       -0.0
6       -0.0
7       -0.0
8     -125.0
9     -320.0
10   -3779.0
11    2482.0
Name: Shrinkage, dtype: float64

Answer 2

You can do this:

df['Shrinkage'] = df['Shrinkage'].str.replace('\$|\)|\,', '')
df['Shrinkage'] = df['Shrinkage'].str.replace('\(', '-')
df['Shrinkage'] = df['Shrinkage'].astype(float)
print(df)


    Shrinkage
0      -614.0
1         0.0
2         0.0
3         0.0
4         0.0
5         0.0
6         0.0
7         0.0
8      -125.0
9       320.0
10     3779.0
11    -2482.0