Generating tuples from DataFrame row elements

Question

I hope this is not me doing something stupid programmatically.

I have a one row Dataframe with numerical Values:

df1                          A            B            C          D

 01-02-2003T00:00:00         5.0         7.0          2.0        4.0   ....

I want to generate a list of tuples based on the values in the dataframe. I do the following:

my_array = numpy.array(df1)

which give me:

           0            1            2          3

 0        5.0          7.0          2.0        4.0   ....

Then I do:

 my_tuple_of_tuples =  tuple((0.5*x, 1.5*x) for x in my_array)

I expect this:

((2.5,7.5),(3.5,10.5),(1.0,3.0),(2.0,6.0))

but I get this:

((2.5,3.5,1.0,2.0),(7.5,10.5,3.0,6.0)) 

What am I doing wrong?

Answer 1

Just index the first row, then your code should work:

tup = tuple((0.5 * x, 1.5 * x) for x in df.values.tolist()[0])
print(tup)
# ((2.5, 7.5), (3.5, 10.5), (1.0, 3.0), (2.0, 6.0))

This works because

df.values.tolist()[0]
# [5.0, 7.0, 2.0, 4.0]

Returns a list of all elements in the first row only. Now, iteration as you do it will work.

---

If you need this to work for multiple rows, you can convert this to a nested loop, or use chain.from_iterable.

from itertools import chain
tup = tuple(
    (0.5 * x, 1.5 * x) for x in chain.from_iterable(df.values.tolist()))
print(tup)
# ((2.5, 7.5), (3.5, 10.5), (1.0, 3.0), (2.0, 6.0))