Slicing an array taking out years

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I have an array which I used np. loadtext on an csv file.

dataresale = np.loadtxt(resale,skiprows=1,usecols=(0,2,10),dtype=[('month','U50'),('flat_type','U50'),
('resale_price','f8')],delimiter=',')

print(dataresale['month'])

Below is the output

['2017-01' '2017-01' '2017-01' ... '2021-03' '2021-10' '2021-12']

I would like to only take out data from year 2021 (all months) only

Below is a script I used to take out rows by year in the another array, but this particular dataset has the months tagged to it

x= datap[datap['year']==2019]

Is there a way I can modify the script above to take out all 2021 data

What I have tried:

x= datap[datap['year']==2019]

Posted 31-Dec-21 18:43pm

Kenny Soon

Updated 2-Jan-22 3:35am

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Comments

Richard MacCutchan 1-Jan-22 4:48am

It is not clear what you are trying to do. If you can extract all the dates for 2019, then the same should hold true for 2021.

0x01AA 1-Jan-22 8:16am

I don't know Python, but this ...

dates = ['2017-01', '2017-01', '2017-01', '2021-03', '2021-10', '2021-12']
years =  [i for i in dates  if i.startswith('2021') ]
print(years)

... prints ['2021-03', '2021-10', '2021-12']

And finally


monthsOfyear =  [i[5:] for i in dates  if i.startswith('2021-') ]

will give you only the months of 2021

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0x01AA · Answer 1 · 2022-01-02T03:35:00

Solution 1

Provided, your example data
['2017-01' '2017-01' '2017-01' ... '2021-03' '2021-10' '2021-12']
is an array (and you simply forgot the commas) the following would extract the months for a give year

Python

dates = ['2017-01', '2017-01', '2017-01', '2021-03', '2021-10', '2021-12']
monthsOfYear =  [i[5:] for i in dates  if i.startswith('2021-') ]
print(monthsOfYear)

and output of the print will be:

['03', '10', '12']

I hope it helps.

Posted 2-Jan-22 3:35am

0x01AA

Updated 2-Jan-22 3:36am

v2

Comments

Richard MacCutchan 2-Jan-22 9:46am

I think it is more complicated than that. The data is loaded using pandas/numpy, which creates tables, rather than simple arrays.

0x01AA 2-Jan-22 9:51am

Thank you for the hint. Now I have to learn about Python tables :-)
Python does fascinate me more and more.

Do you think it is better to delete the answer?

Richard MacCutchan 2-Jan-22 10:05am

Leave the answer, it may encourage OP to provide a better explanation.

I find Python quite fun also, once you get used to its crazy syntax.

0x01AA 2-Jan-22 13:18pm

Thanks, so I will leave the answer.

For me (c++ programmer) just already only the python 'slice' stuff is great. And also the things what numpy supports is incredible. And the syntax basically I think is very ok (at least for me), only the thing with the indentations I hate ;)