Numpy/Pandas: Error converting ndarray to series

Question

I have the ndarray "diffTemp":

diffTemp = np.diff([df.Temp])

Where Temp are temperature values whose differences I compute using the difference operator. In this case using print() I get:

print(diffTemp) = [[-0.16 -0.05]]

To convert it into a column vector I use:

diffTemp = diffTemp.transpose()

And then convert is from ndarray into Series using:

diffTemp = pd.Series([diffTemp])

(This allows me later to concatenate diffTime with its corresponding Series dates (diffDates).)

Unfortunately this outputs that diffTemp is:

print(diffTemp) = 0    [[-0.16000000000000014], [-0.05000000000000071]]

If I instead use (i.e. without hard brackets [ ]), such that instead:

diffTemp = pd.Series(diffTemp)

I instead get the error message:

Exception: Data must be 1-dimensional

Totally new to Python and have tried google the last few days without any success. Any help is much much appreciated.

steven_monaghan · Accepted Answer · 2019-11-25 18:27:11Z

1

The issue here is that you are trying to convert a two-dimensional array into a 1-dimensional series. Notice that there are two brackets around [[-0.16 -0.05]]. You can write the following to get back a series by just grabbing the 1-d array that you want:

diffTemp = pd.Series(diffTemp[0])

answered Nov 25, 2019 at 18:27

steven_monaghan

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1 Comment

litmus Over a year ago

Thank you so much!! That is brilliant, I had lost track of the dimensions

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