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Ilyz
Ilyz

Reputation: 23

Repeat specific range value in column and show in dataframe

I am newborn in python. Kindly help me in the following query:-

There are 8760 records(rows) in my dataframe (df) such that

Temperature
    5      
   10      
    8
    3
    1
    .
    .
    .

I want to assign specific range value (either 1 to 7 or 1 to 365) to new column and then repeat this range up to last records in the same column. The expected result is to be like this: 

DayNumber
    1
    2
    3
    4
    5
    6
    7
    1
    2
    3
    4
    5
    6
    7
    1
    2
    3
    .
    .
    .

How do I achieve this kind of output?

Upvotes: 1

Views: 842

Answers (3)

anky
anky

Reputation: 75080

Simplest method:

You can make a list of 1-7 by :

a = list(np.arange(7)+1)

Then use:

from itertools import cycle, islice
df['DayNumber'] = list(islice(cycle(a), len(df)))

This will allow you to cycle your list for n number of times here which is the length of your dataframe.

Time taken for 365 entries:

%timeit list(islice(cycle(a), len(df)))
#6.26 µs ± 78.5 ns per loop (mean ± std. dev. of 7 runs, 100000 loops each)

Upvotes: 0

Ananay Mital
Ananay Mital

Reputation: 1475

This seems easier

df = pd.DataFrame([range(10)]).T
df.columns = ["Temperature"]
df

   Temperature
0   0
1   1
2   2
3   3
4   4
5   5
6   6
7   7
8   8
9   9

n=7
ll = pd.DataFrame(range(1, n+1)*(len(df)/n +1))
ll

    0
0   1
1   2
2   3
3   4
4   5
5   6
6   7
7   1
8   2
9   3
10  4
11  5
12  6
13  7

df.join(ll)

    Temperature  0
0   0            1
1   1            2
2   2            3
3   3            4
4   4            5
5   5            6
6   6            7
7   7            1
8   8            2
9   9            3

Upvotes: 0

James Chang
James Chang

Reputation: 630

My method is easier for you to understand. Since I do not have the data, I assume the temperature is always 10 degrees Celsius. You can change it with yours.

import pandas as pd
temperature = [10] * 8760
days = []
row = 1
day = 1
while row <= 8760:
    days.append(day)
    day += 1
    row += 1
    if day == 8:
        day = 1
data = {"temperature": temperature, "day": days}
df = pd.DataFrame(data=data)

Upvotes: 1

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