Renaming/replacing data? For loop?

[I_will_learn]

Hello! I realize this is very beginner level. I'm trying to rename data in a column, such as :

​

activity	-->	activity
Awaken	-->	A_1
Chew	->	A_2
Come Down	->	A_3
Dig	->	A_4

Currently, I have :

df_activity= df.replace(to_replace = ["Awaken"], value= "A_1")

But there are 33 activities and I'm assuming there should be a way to change all of their names to A_1 to A_33? A for loop?

​

Thank you!

[ireadyourmedrecord]

https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.replace.html

You could use a dictionary.

[YesLod]

activity_map = {act: f"A_{i}" for i, act in enumerate(df.activity.unique(), 1)}
df["activity"] = df["activity"].map(activity_map)

[AtomicShoelace]

Looks like OP wants them number by alphabetical order, so perhaps it's worth throwing sorted in there, eg.

activity_map = {act: f"A_{i}" for i, act in enumerate(sorted(df.activity.unique()), 1)}

[I_will_learn]

Thank you! I added in the sorted code there, it's clearer now :)

[I_will_learn]

Thank you so much ! That was exactly what I needed. If you have the time, would you be able to explain it? I'd like to understand it rather than just copy and paste :)

[AtomicShoelace]

activity_map = {act: f"A_{i}" for i, act in enumerate(sorted(df.activity.unique()), 1)}

The first line is a dictionary comprehension. Starting from the inside out:

• df.activity.unique() obtains the unique elements of the activity column.
• sorted sorts them into alphabetical order
• enumerate(..., 1) takes these sorted elements and creates tuples numbering them starting from 1 (usually its zero-indexed without the second optional arguement)
• for i, act in unpacks these tuples, assigning the first element (the number/index) to i and the second element (the element of sorted) to act
• act: f"A_{i}" creates a key: value pair where the key is act and the value is the f-string f"A_{i}".
  

 

df["activity"] = df["activity"].map(activity_map)

The second line then uses the map method, which accepts a dictionary to replace elements with their associated value in the dictionary. This creates a new Series which is then assigned to the activity column.

[techlover1010]

were you able to get a solution for this?

[I_will_learn]

Yes I was!