CODEWITHSUNDEEP
pythonpandas
Hello lad
Hello lad

Reputation: 18790

apply function on dataframe involving two rows

I have a pandas DataFrame with 3 columns and milion rows:

    time      longitude      latitude
    1         x1              y1
    2         x2              y2
    3         x3              y3
    ...

I want to apply a function to calculate distance based on the longitude and latitude. Basically I need a way to express the function can handle two adjacent rows in dataframe like 

    compute_distance(x1,y1,x2,y2)

I know there are ways to apply function along axis 1 and 0, but they seem only apply to single row or column. How can I express something involving several rows or columns.

Upvotes: 1

Views: 2003

Answers (1)

Michael WS
Michael WS

Reputation: 2617

Apply won't be able to this, but you can do something simple like the following:

def compute_distance(df):
    next_df = df.shift(-1)
    return distance_on_unit_sphere(df["lat"], df["long"],
                                   next_df["lat"], next_df["long"]):

from here http://www.johndcook.com/python_longitude_latitude.html

Upvotes: 1

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