How do I execute my function on an array of data in Python?

Question

In MATLAB, if I write my own function I can pass an array to that function and it automagically just deals with it. I'm trying to do the same thing in Python, the other Data Science language, and it's not dealing with it.

Is there an easy way to do this without having to make loops every time I want to operate on all values in an array? That's a lot more work! It seems like the great minds working in Python would have had something like this need before.

I tried switching the data type to a list() since that's iterable, but that didn't seem to work. I'm still getting an error that basically says it doesn't want an array object.

Here's my code:

import scipy
from collections import deque
import numpy as np
import os
from datetime import date, timedelta

def GetExcelData(filename,rowNum,titleCol):
    csv = np.genfromtxt(filename, delimiter= ",")
    Dates = deque(csv[rowNum,:])
    if titleCol == True:
        Dates.popleft()
    return list(Dates)

def from_excel_ordinal(ordinal, _epoch=date(1900, 1, 1)):
    if ordinal > 59: #the function stops working here when I pass my array
        ordinal -= 1  # Excel leap year bug, 1900 is not a leap year!
    return _epoch + timedelta(days=ordinal - 1)  # epoch is day 1

os.chdir("C:/Users/blahblahblah")
filename = "SamplePandL.csv"
Dates = GetExcelData(filename,1,1)
Dates = from_excel_ordinal(Dates) #this is the call with an issue
print(Dates)

I think the magic you might be looking for is in numpy. For instance, you could do that if statement with numpy.where. — Bill Bell
– Bill Bell, Commented Mar 10, 2017 at 4:04
If your list is one dimensional, maybe you could try something like map(from_excel_ordinal, Dates). It would apply said function to every element. — Tristan
– Tristan, Commented Mar 10, 2017 at 4:20
you can use map or lambda to do the same, for map just use like Dates = list(map(from_excel_ordinal,Dates)) — Aman Jaiswal
– Aman Jaiswal, Commented Mar 10, 2017 at 5:08

Kaushal Kumar Singh · Accepted Answer · 2017-03-10 04:36:44Z

1

Well you can use map function for that.

Dates = from_excel_ordinal(Dates)

Replace the above line from the code with the following code

Dates = list(map(from_excel_ordinal,Dates))

In the above code, for each value present in Dates, function from_excel_ordinal will be called. Finally it gets converted into list and stored into Dates.

edited Mar 10, 2017 at 4:36

answered Mar 10, 2017 at 4:30

Kaushal Kumar Singh

82911 silver badges19 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How do I execute my function on an array of data in Python?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related