I have a list of 41 data from a functioned I defined, but I only want to access the first 40 of them. So, the index positions I am looking for are from 0 - 39
forecast_price(10)[:len(forecast_price(10)) - 1]
I also made it a variable for easier reference further on in my codes:
forecast_w10 = forecast_price(10)[:len(forecast_price(10)) - 1]
However, when I try printing the length of data in the variable, I still get 41. I feel like the mistake is right under my nose but can't seem to figure it out. What am I doing wrong?
In[46]: print(len(forecast_w10))
Out[46]: 41
For reproducibility, let's assume forecast_price is a function that returns a list of 41 elements, starting at a given initial value x:
def forecast_price(x):
return [i + x for i in range(41)]
print(forecast_price(1)) # [1, 2, 3, ..., 39, 40, 41]
print(len(forecast_price(1))) # 41
print(forecast_price(10)) # [10, 11, 12, ..., 48, 49, 50]
print(len(forecast_price(10))) # 41
Since you want to access only the 40 first values, use the slicing operator:
forecast_w10 = forecast_price(10)[:40]
print(forecast_w10) # [10, 11, 12, ..., 47, 48, 49]
print(len(forecast_w10)) # 40