How do I increment value based on value in column and everytime I increment return the value to another column. Pandas

Question

I am currently doing a data analysis internship at a small company and I have to clean up some data using python and pandas. One of the requests was to add a column that has device #1 in correlating with Site #... So when Site # is 0 device #1 is in the following column and when Site # is 1 device #2 is in the following column. The kicker is the device number increases throughout the 350,000 rows and I need to increment the device # up everytime I come across the next set of device numbers. Before the next set of device #'s so in this case 3,4 which is after 1,2 there is a cell with '======' that I use as an indicator to increment up to 3,4 and so on. However I can never get my code to properly increment up to the next set of device #'s when it comes across the indicator.

def z(x):
    b=1
    if df['Site'] != '======':
        x == 0: return b
        x == 1: return b + 1
    if df['Site'] == '======':
        b += 2
df['Device #'] = df['Site'].apply(z)

Answer 1

This is how this is done:

b=0
def increment(i):

    global b

    if i == 0:
        return i

    elif i == "=====":
        b += 2 
        i += b
    
    elif i ==1:
        i += 1
    
    return i

df["Device #"] = df["Site"].map(increment)

Or if you insist on using apply, you can do it this way:

df["Device #"] = df["Site"].apply(increment, axis = 1)