I have a pandas df, like this:
ID date value
0 10 2022-01-01 100
1 10 2022-01-02 150
2 10 2022-01-03 0
3 10 2022-01-04 0
4 10 2022-01-05 200
5 10 2022-01-06 0
6 10 2022-01-07 150
7 10 2022-01-08 0
8 10 2022-01-09 0
9 10 2022-01-10 0
10 10 2022-01-11 0
11 10 2022-01-12 100
12 23 2022-02-01 490
13 23 2022-02-02 0
14 23 2022-02-03 350
15 23 2022-02-04 333
16 23 2022-02-05 0
17 23 2022-02-06 0
18 23 2022-02-07 0
19 23 2022-02-08 211
20 23 2022-02-09 100
I would like calculate the days of last value. Like the bellow example. How can I using diff() for this? And the calculus change by ID.
Output:
ID date value days_last_value
0 10 2022-01-01 100 0
1 10 2022-01-02 150 1
2 10 2022-01-03 0
3 10 2022-01-04 0
4 10 2022-01-05 200 3
5 10 2022-01-06 0
6 10 2022-01-07 150 2
7 10 2022-01-08 0
8 10 2022-01-09 0
9 10 2022-01-10 0
10 10 2022-01-11 0
11 10 2022-01-12 100 5
12 23 2022-02-01 490 0
13 23 2022-02-02 0
14 23 2022-02-03 350 2
15 23 2022-02-04 333 1
16 23 2022-02-05 0
17 23 2022-02-06 0
18 23 2022-02-07 0
19 23 2022-02-08 211 4
20 23 2022-02-09 100 1
Explanation below.
import pandas as pd
df = pd.DataFrame({'ID': 12 * [10] + 9 * [23],
'value': [100, 150, 0, 0, 200, 0, 150, 0, 0, 0, 0, 100, 490, 0, 350, 333, 0, 0, 0, 211, 100]})
days = df.groupby(['ID', (df['value'] != 0).cumsum()]).size().groupby('ID').shift(fill_value=0)
days.index = df.index[df['value'] != 0]
df['days_last_value'] = days
df
ID value days_last_value
0 10 100 0.0
1 10 150 1.0
2 10 0 NaN
3 10 0 NaN
4 10 200 3.0
5 10 0 NaN
6 10 150 2.0
7 10 0 NaN
8 10 0 NaN
9 10 0 NaN
10 10 0 NaN
11 10 100 5.0
12 23 490 0.0
13 23 0 NaN
14 23 350 2.0
15 23 333 1.0
16 23 0 NaN
17 23 0 NaN
18 23 0 NaN
19 23 211 4.0
20 23 100 1.0
First, we'll have to group by 'ID'.
We also creates groups for each block of days, by creating a True/False series where value is not 0, then performing a cumulative sum. That is the part (df['value'] != 0).cumsum(), which results in
0 1
1 2
2 2
3 2
4 3
5 3
6 4
7 4
8 4
9 4
10 4
11 5
12 6
13 6
14 7
15 8
16 8
17 8
18 8
19 9
20 10
We can use the values in this series to also group on; combining that with the 'ID' group, you have the individual blocks of days. This is the df.groupby(['ID', (df['value'] != 0).cumsum()]) part.
Now, for each block, we get its size, which is obviously the interval in days; which is what you want. We do need to shift one up, since we've counted the total number of days per group, and the difference would be one less; and fill with 0 at the bottom. But this shift has to be by ID group, so we first group by ID again before shifting (as we lost the grouping after doing .size()).
Now, this new series needs to get assigned back to the dataframe, but it's obviously shorter. Since its index it also reset, we can't easily reassign it (not with df['days_last_value'], df.loc[...] or df.iloc).
Instead, we select the index values of the original dataframe where value is not zero, and set the index of the days equal to that.
Now, it's easy step to directly assign the days to relevant column in the dataframe: Pandas will match the indices.
Related
I have a dataframe like this:
DATE MIN_AMOUNT MAX_AMOUNT MIN_DAY MAX_DAY
01/09/2022 10 20 1 2
01/09/2022 15 25 4 5
01/09/2022 30 50 7 10
05/09/2022 10 20 1 2
05/09/2022 15 25 4 5
07/09/2022 15 25 4 5
I want to expand the dataframe to all date range between the DATE column with forward filling. The desired putput is:
DATE MIN_AMOUNT MAX_AMOUNT MIN_DAY MAX_DAY
01/09/2022 10 20 1 2
01/09/2022 15 25 4 5
01/09/2022 30 50 7 10
02/09/2022 10 20 1 2
02/09/2022 15 25 4 5
02/09/2022 30 50 7 10
03/09/2022 10 20 1 2
03/09/2022 15 25 4 5
03/09/2022 30 50 7 10
04/09/2022 10 20 1 2
04/09/2022 15 25 4 5
04/09/2022 30 50 7 10
05/09/2022 10 20 1 2
05/09/2022 15 25 4 5
06/09/2022 10 20 1 2
06/09/2022 15 25 4 5
07/09/2022 15 25 4 5
Could you please help me about this?
First convert values to datetimes, create helper counter Series g by GroupBy.cumcount for reshape by DataFrame.set_index and DataFrame.unstack, then use DataFrame.asfreq with method='ffill' and reshape back by DataFrame.stack, remove helper level by DataFrame.droplevel, convert DatetimeIndex to column, change format of datetimes and last create same dtypes like original DataFrame:
df['DATE'] = pd.to_datetime(df['DATE'], dayfirst=True)
g = df.groupby('DATE').cumcount()
df = (df.set_index(['DATE',g])
.unstack()
.asfreq('D', method='ffill')
.stack()
.droplevel(-1)
.reset_index()
.assign(DATE = lambda x: x['DATE'].dt.strftime('%d/%m/%Y'))
.astype(df.dtypes)
)
print (df)
DATE MIN_AMOUNT MAX_AMOUNT MIN_DAY MAX_DAY
0 2022-01-09 10 20 1 2
1 2022-01-09 15 25 4 5
2 2022-01-09 30 50 7 10
3 2022-02-09 10 20 1 2
4 2022-02-09 15 25 4 5
5 2022-02-09 30 50 7 10
6 2022-03-09 10 20 1 2
7 2022-03-09 15 25 4 5
8 2022-03-09 30 50 7 10
9 2022-04-09 10 20 1 2
10 2022-04-09 15 25 4 5
11 2022-04-09 30 50 7 10
12 2022-05-09 10 20 1 2
13 2022-05-09 15 25 4 5
14 2022-06-09 10 20 1 2
15 2022-06-09 15 25 4 5
16 2022-07-09 15 25 4 5
A couple of merges should help with this, and should still be efficient as the data size increases:
Get the unique dates and build a new dataframe from that:
out = df.DATE.drop_duplicates()
dates = pd.date_range(out.min(), out.max(), freq='D')
dates = pd.DataFrame(dates, columns=['dates'])
Merge dates with out, and subsequently merge the outcome with the original dataframe:
(dates
.merge(
out,
left_on='dates',
right_on='DATE',
how = 'left')
# faster to fill on a Series than a Dataframe
.assign(DATE = lambda df: df.DATE.ffill())
.merge(
df,
on = 'DATE',
how = 'left')
.drop(columns='DATE')
.rename(columns= {'dates':'DATE'})
)
DATE MIN_AMOUNT MAX_AMOUNT MIN_DAY MAX_DAY
0 2022-09-01 10 20 1 2
1 2022-09-01 15 25 4 5
2 2022-09-01 30 50 7 10
3 2022-09-02 10 20 1 2
4 2022-09-02 15 25 4 5
5 2022-09-02 30 50 7 10
6 2022-09-03 10 20 1 2
7 2022-09-03 15 25 4 5
8 2022-09-03 30 50 7 10
9 2022-09-04 10 20 1 2
10 2022-09-04 15 25 4 5
11 2022-09-04 30 50 7 10
12 2022-09-05 10 20 1 2
13 2022-09-05 15 25 4 5
14 2022-09-06 10 20 1 2
15 2022-09-06 15 25 4 5
16 2022-09-07 15 25 4 5
I have a column as follows:
A B
0 0 20.00
1 1 35.00
2 2 75.00
3 3 29.00
4 4 125.00
5 5 16.00
6 6 52.50
7 7 NaN
8 8 NaN
9 9 NaN
10 10 NaN
11 11 NaN
12 12 NaN
13 13 239.91
14 14 22.87
15 15 52.74
16 16 37.20
17 17 27.44
18 18 57.01
19 19 29.88
I want to change the values of the column as follows
if 0<B<10.0, then Replace the cell value of B by "0 to 10"
if 10.1<B<20.0, then Replace the cell value of B by "10 to 20"
continue like this until the maximum range achieved.
I have tried
ds['B'] = np.where(ds['B'].between(10.0,20.0), "10 to 20", ds['B'])
But once I perform this operation, the DataFrame is occupied by the string "10 to 20" so I cannot perform this operation again for the remaining values of the DataFrame. After this step, the DataFrame looks like this:
A B
0 0 10 to 20
1 1 35.0
2 2 75.0
3 3 29.0
4 4 125.0
5 5 10 to 20
6 6 52.5
7 7 nan
8 8 nan
9 9 nan
10 10 nan
11 11 nan
12 12 nan
13 13 239.91
14 14 22.87
15 15 52.74
16 16 37.2
17 17 27.44
18 18 57.01
19 19 29.88
And the following line: ds['B'] = np.where(ds['B'].between(20.0,30.0), "20 to 30", ds['B']) will throw TypeError: '>=' not supported between instances of 'str' and 'float'
How can i code this to change all of the values in the DataFrame to these strings of ranges all at once?
Build your bins and labels and use pd.cut:
bins = np.arange(0, df["B"].max() // 10 * 10 + 10, 10).astype(int)
labels = [' to '.join(t) for t in zip(bins[:-1].astype(str), bins[1:].astype(str))]
df["B"] = pd.cut(df["B"], bins=bins, labels=labels)
>>> df
A B
0 0 10 to 20
1 1 30 to 40
2 2 70 to 80
3 3 20 to 30
4 4 120 to 130
5 5 10 to 20
6 6 50 to 60
7 7 NaN
8 8 NaN
9 9 NaN
10 10 NaN
11 11 NaN
12 12 NaN
13 13 NaN
14 14 20 to 30
15 15 50 to 60
16 16 30 to 40
17 17 20 to 30
18 18 50 to 60
19 19 20 to 30
This can be done with much less code as this is actually just a matter of string formatting.
ds['B'] = ds['B'].apply(lambda x: f'{int(x/10) if x>=10 else ""}0 to {int(x/10)+1}0' if pd.notnull(x) else x)
You can create a custom function that maps each range to a string. For example, 19.0 will be mapped to "10 to 20", and then apply this function to each row.
I've written the code so that the minimum and maximum of the range is generalizable to the DataFrame, and takes on values that are multiples of 10.
import numpy as np
import pandas as pd
## copy and paste your DataFrame
ds = pd.read_clipboard()
# floor to nearest multiple of 10
ds_min = ds['B'].min()//10*10
# ceiling to the nearest multiple of 10
ds_max = round(ds['B'].max(),-1)
ranges = np.linspace(ds_min, ds_max, ((ds_max-ds_min)/10)+1)
def map_value_to_string(value):
for idx in range(1,len(ranges)):
low_value, high_value = ranges[idx-1], ranges[idx]
if low_value < value <= high_value:
return f"{int(low_value)} to {int(high_value)}"
else:
continue
ds['B'] = ds['B'].apply(lambda x: map_value_to_string(x))
Output:
>>> ds
A B
0 0 10 to 20
1 1 30 to 40
2 2 70 to 80
3 3 20 to 30
4 4 120 to 130
5 5 10 to 20
6 6 50 to 60
7 7 None
8 8 None
9 9 None
10 10 None
11 11 None
12 12 None
13 13 230 to 240
14 14 20 to 30
15 15 50 to 60
16 16 30 to 40
17 17 20 to 30
18 18 50 to 60
19 19 20 to 30
So I have a data frame that is something like this
Resource 2020-06-01 2020-06-02 2020-06-03
Name1 8 7 8
Name2 7 9 9
Name3 10 10 10
Imagine that the header is literal all the days of the month. And that there are way more names than just three.
I need to reduce the columns to five. Considering the first column to be the days between 2020-06-01 till 2020-06-05. Then from Saturday till Friday of the same week. Or the last day of the month if it is before Friday. So for June would be these weeks:
week 1: 2020-06-01 to 2020-06-05
week 2: 2020-06-06 to 2020-06-12
week 3: 2020-06-13 to 2020-06-19
week 4: 2020-06-20 to 2020-06-26
week 5: 2020-06-27 to 2020-06-30
I have no problem defining these weeks. The problem is grouping the columns based on them.
I couldn't come up with anything.
Does someone have any ideas about this?
I have to use these code to generate your dataframe.
dates = pd.date_range(start='2020-06-01', end='2020-06-30')
df = pd.DataFrame({
'Name1': np.random.randint(1, 10, size=len(dates)),
'Name2': np.random.randint(1, 10, size=len(dates)),
'Name3': np.random.randint(1, 10, size=len(dates)),
})
df = df.set_index(dates).transpose().reset_index().rename(columns={'index': 'Resource'})
Then, the solution starts from here.
# Set the first column as index
df = df.set_index(df['Resource'])
# Remove the unused column
df = df.drop(columns=['Resource'])
# Transpose the dataframe
df = df.transpose()
# Output:
Resource Name1 Name2 Name3
2020-06-01 00:00:00 3 2 7
2020-06-02 00:00:00 5 6 8
2020-06-03 00:00:00 2 3 6
...
# Bring "Resource" from index to column
df = df.reset_index()
df = df.rename(columns={'index': 'Resource'})
# Add a column "week of year"
df['week_no'] = df['Resource'].dt.weekofyear
# You can simply group by the week no column
df.groupby('week_no').sum().reset_index()
# Output:
Resource week_no Name1 Name2 Name3
0 23 38 42 41
1 24 37 30 43
2 25 38 29 23
3 26 29 40 42
4 27 2 8 3
I don't know what you want to do for the next. If you want your original form, just transpose() it back.
EDIT: OP claimed the week should start from Saturday end up with Friday
# 0: Monday
# 1: Tuesday
# 2: Wednesday
# 3: Thursday
# 4: Friday
# 5: Saturday
# 6: Sunday
df['weekday'] = df['Resource'].dt.weekday.apply(lambda day: 0 if day <= 4 else 1)
df['customised_weekno'] = df['week_no'] + df['weekday']
Output:
Resource Resource Name1 Name2 Name3 week_no weekday customised_weekno
0 2020-06-01 4 7 7 23 0 23
1 2020-06-02 8 6 7 23 0 23
2 2020-06-03 5 9 5 23 0 23
3 2020-06-04 7 6 5 23 0 23
4 2020-06-05 6 3 7 23 0 23
5 2020-06-06 3 7 6 23 1 24
6 2020-06-07 5 4 4 23 1 24
7 2020-06-08 8 1 5 24 0 24
8 2020-06-09 2 7 9 24 0 24
9 2020-06-10 4 2 7 24 0 24
10 2020-06-11 6 4 4 24 0 24
11 2020-06-12 9 5 7 24 0 24
12 2020-06-13 2 4 6 24 1 25
13 2020-06-14 6 7 5 24 1 25
14 2020-06-15 8 7 7 25 0 25
15 2020-06-16 4 3 3 25 0 25
16 2020-06-17 6 4 5 25 0 25
17 2020-06-18 6 8 2 25 0 25
18 2020-06-19 3 1 2 25 0 25
So, you can use customised_weekno for grouping.
import pandas as pd
import numpy as np
df1=pd.DataFrame(np.arange(25).reshape((5,5)),index=pd.date_range('2015/01/01',periods=5,freq='D')))
df1['trading_signal']=[1,-1,1,-1,1]
df1
0 1 2 3 4 trading_signal
2015-01-01 0 1 2 3 4 1
2015-01-02 5 6 7 8 9 -1
2015-01-03 10 11 12 13 14 1
2015-01-04 15 16 17 18 19 -1
2015-01-05 20 21 22 23 24 1
and
df2
0 1 2 3 4
Date Time
2015-01-01 22:55:00 0 1 2 3 4
23:55:00 5 6 7 8 9
2015-01-02 00:55:00 10 11 12 13 14
01:55:00 15 16 17 18 19
02:55:00 20 21 22 23 24
how would I get the value of trading_signal from df1 and sent it to df2.
I want an output like this:
0 1 2 3 4 trading_signal
Date Time
2015-01-01 22:55:00 0 1 2 3 4 1
23:55:00 5 6 7 8 9 1
2015-01-02 00:55:00 10 11 12 13 14 -1
01:55:00 15 16 17 18 19 -1
02:55:00 20 21 22 23 24 -1
You need to either merge or join. If you merge you need to reset_index, which is less memory efficient ans slower than using join. Please read the docs on Joining a single index to a multi index:
New in version 0.14.0.
You can join a singly-indexed DataFrame with a level of a
multi-indexed DataFrame. The level will match on the name of the index
of the singly-indexed frame against a level name of the multi-indexed
frame
If you want to use join, you must name the index of df1 to be Date so that it matches the name of the first level of df2:
df1.index.names = ['Date']
df1[['trading_signal']].join(df2, how='right')
trading_signal 0 1 2 3 4
Date Time
2015-01-01 22:55:00 1 0 1 2 3 4
23:55:00 1 5 6 7 8 9
2015-01-02 00:55:00 -1 10 11 12 13 14
01:55:00 -1 15 16 17 18 19
02:55:00 -1 20 21 22 23 24
I'm joining right for a reason, if you don't understand what this means please read Brief primer on merge methods (relational algebra).
The goal here is to see how many unique values i have in my database. This is the code i have written:
apps = pd.read_csv('ConcatOwned1_900.csv', sep='\t', usecols=['appid'])
apps[('appid')] = apps[('appid')].astype(int)
apps_list=apps['appid'].unique()
b = apps.groupby('appid').size()
blist = b.unique()
print len(apps_list), len(blist), len(set(b))
>>>7672 2164 2164
Why is there difference in those two methods?
Due to request i am posting some of my data:
Unnamed: 0 StudID No appid work work2
0 0 76561193665298433 0 10 nan 0
1 1 76561193665298433 1 20 nan 0
2 2 76561193665298433 2 30 nan 0
3 3 76561193665298433 3 40 nan 0
4 4 76561193665298433 4 50 nan 0
5 5 76561193665298433 5 60 nan 0
6 6 76561193665298433 6 70 nan 0
7 7 76561193665298433 7 80 nan 0
8 8 76561193665298433 8 100 nan 0
9 9 76561193665298433 9 130 nan 0
10 10 76561193665298433 10 220 nan 0
11 11 76561193665298433 11 240 nan 0
12 12 76561193665298433 12 280 nan 0
13 13 76561193665298433 13 300 nan 0
14 14 76561193665298433 14 320 nan 0
15 15 76561193665298433 15 340 nan 0
16 16 76561193665298433 16 360 nan 0
17 17 76561193665298433 17 380 nan 0
18 18 76561193665298433 18 400 nan 0
19 19 76561193665298433 19 420 nan 0
20 20 76561193665298433 20 500 nan 0
21 21 76561193665298433 21 550 nan 0
22 22 76561193665298433 22 620 6.0 3064
33 33 76561193665298434 0 10 nan 837
34 34 76561193665298434 1 20 nan 27
35 35 76561193665298434 2 30 nan 9
36 36 76561193665298434 3 40 nan 5
37 37 76561193665298434 4 50 nan 2
38 38 76561193665298434 5 60 nan 0
39 39 76561193665298434 6 70 nan 403
40 40 76561193665298434 7 130 nan 0
41 41 76561193665298434 8 80 nan 6
42 42 76561193665298434 9 100 nan 10
43 43 76561193665298434 10 220 nan 14
IIUC based on attached piece of the dataframe it seems that you should analyze b.index, not values of b. Just look:
b = apps.groupby('appid').size()
In [24]: b
Out[24]:
appid
10 2
20 2
30 2
40 2
50 2
60 2
70 2
80 2
100 2
130 2
220 2
240 1
280 1
300 1
320 1
340 1
360 1
380 1
400 1
420 1
500 1
550 1
620 1
dtype: int64
In [25]: set(b)
Out[25]: {1, 2}
But if you do it for b.index you'll get the same values for all 3 methods:
blist = b.index.unique()
In [30]: len(apps_list), len(blist), len(set(b.index))
Out[30]: (23, 23, 23)