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Joining 2 dataframe based on a column [duplicate]

This question already has answers here:
Pandas Merging 101
(8 answers)
Closed 11 months ago.
Following is one of my dataframe structure:
strike coi chgcoi
120 200 20
125 210 15
130 230 12
135 240 9
and the other one is:
strike poi chgpoi
125 210 15
130 230 12
135 240 9
140 225 12
What I want is:
strike coi chgcoi strike poi chgpoi
120 200 20 120 0 0
125 210 15 125 210 15
130 230 12 130 230 12
135 240 9 135 240 9
140 0 0 140 225 12

First, you need to create two dataframes using pandas
df1 = pd.Dataframe({'column_1': [val_1, val_2, ..., val_n], 'column_2':[val_1, val_2, ..., val_n]})
df2 = pd.Dataframe({'column_1': [val_1, val_2, ..., val_n], 'column_2':[val_1, val_2, ..., val_n]})
Then you can use outer join
df1.merge(df2, on='common_column_name', how='outer')

db1
strike coi chgcoi
0 120 200 20
1 125 210 15
2 130 230 12
3 135 240 9
db2
strike poi chgpoi
0 125 210 15
1 130 230 12
2 135 240 9
3 140 225 12
merge = db1.merge(db2,how="outer",on='strike')
merge
strike coi chgcoi poi chgpoi
0 120 200.0 20.0 NaN NaN
1 125 210.0 15.0 210.0 15.0
2 130 230.0 12.0 230.0 12.0
3 135 240.0 9.0 240.0 9.0
4 140 NaN NaN 225.0 12.0
merge.fillna(0)
strike coi chgcoi poi chgpoi
0 120 200.0 20.0 0.0 0.0
1 125 210.0 15.0 210.0 15.0
2 130 230.0 12.0 230.0 12.0
3 135 240.0 9.0 240.0 9.0
4 140 0.0 0.0 225.0 12.0
This is your expected result with the only difference that 'strike' is not repeated

How to add additional text to matplotlib annotations

I have used seaborn's titanic dataset as a proxy for my very large dataset to create the chart and data based on that.
The following code runs without any errors:
import seaborn as sns
import pandas as pd
import numpy as np
sns.set_theme(style="darkgrid")
# Load the example Titanic dataset
df = sns.load_dataset("titanic")
# split fare into decile groups and order them
df['fare_grp'] = pd.qcut(df['fare'], q=10,labels=None, retbins=False, precision=0).astype(str)
df.groupby(['fare_grp'],dropna=False).size()
df['fare_grp_num'] = pd.qcut(df['fare'], q=10,labels=False, retbins=False, precision=0).astype(str)
df.groupby(['fare_grp_num'],dropna=False).size()
df['fare_ord_grp'] = df['fare_grp_num'] + ' ' +df['fare_grp']
df['fare_ord_grp']
# set variables
target = 'survived'
ydim = 'fare_ord_grp'
xdim = 'embark_town'
#del [result]
non_events = pd.DataFrame(df[df[target]==0].groupby([ydim,xdim],as_index=False, dropna=False)[target].count()).rename(columns={target: 'non_events'})
non_events[xdim]=non_events[xdim].replace(np.nan, 'Missing', regex=True)
non_events[ydim]=non_events[ydim].replace(np.nan, 'Missing', regex=True)
non_events_total = pd.DataFrame(df[df[target]==0].groupby([xdim],dropna=False,as_index=False)[target].count()).rename(columns={target: 'non_events_total_by_xdim'}).replace(np.nan, 'Missing', regex=True)
events = pd.DataFrame(df[df[target]==1].groupby([ydim,xdim],as_index=False, dropna=False)[target].count()).rename(columns={target: 'events'})
events[xdim]=events[xdim].replace(np.nan, 'Missing', regex=True)
events[ydim]=events[ydim].replace(np.nan, 'Missing', regex=True)
events_total = pd.DataFrame(df[df[target]==1].groupby([xdim],dropna=False,as_index=False)[target].count()).rename(columns={target: 'events_total_by_xdim'}).replace(np.nan, 'Missing', regex=True)
grand_total = pd.DataFrame(df.groupby([xdim],dropna=False,as_index=False)[target].count()).rename(columns={target: 'total_by_xdim'}).replace(np.nan, 'Missing', regex=True)
grand_total=grand_total.merge(non_events_total, how='left', on=xdim).merge(events_total, how='left', on=xdim)
result = pd.merge(non_events, events, how="outer",on=[ydim,xdim])
result['total'] = result['non_events'].fillna(0) + result['events'].fillna(0)
result[xdim] = result[xdim].replace(np.nan, 'Missing', regex=True)
result = pd.merge(result, grand_total, how="left",on=[xdim])
result['survival rate %'] = round(result['events']/result['total']*100,2)
result['% event dist by xdim'] = round(result['events']/result['events_total_by_xdim']*100,2)
result['% non-event dist by xdim'] = round(result['non_events']/result['non_events_total_by_xdim']*100,2)
result['% total dist by xdim'] = round(result['total']/result['total_by_xdim']*100,2)
display(result)
value_name1 = "% dist by " + str(xdim)
dfl = pd.melt(result, id_vars=[ydim, xdim],value_vars =['% total dist by xdim'], var_name = 'Type',value_name=value_name1).drop(columns='Type')
dfl2 = dfl.pivot(index=ydim, columns=xdim, values=value_name1)
print(dfl2)
title1 = "% dist by " + str(xdim)
ax=dfl2.T.plot(kind='bar', stacked=True, rot=1, figsize=(8, 8), title=title1)
ax.set_xticklabels(ax.get_xticklabels(), rotation=45)
ax.legend(bbox_to_anchor=(1.0, 1.0),title = 'Fare Range')
ax.set_ylabel('% Dist')
for p in ax.patches:
width, height = p.get_width(), p.get_height()
x, y = p.get_xy()
ax.text(x+width/2, y+height/2,'{:.0f}%'.format(height),horizontalalignment='center', verticalalignment='center')
It produces the following stacked percent bar chart, which shows the % of total distribution by embark town.
I also want to show the survival rate along with the %distribution in each block. For example, for Queenstown, fare range 1 (7.6, 7.9], the % total distribution is 56%. I want to display the survival rate 37.21% as (56%, 37.21%). I am not able to figure it out. Kindly offer any suggestions. Thanks.
Here is the output summary table for reference
fare_ord_grp
embark_town
non_events
events
total
total_by_xdim
non_events_total_by_xdim
events_total_by_xdim
survival rate %
% event dist by xdim
% non-event dist by xdim
% total dist by xdim
0
0 (-0.1,7.6]
Cherbourg
22
7
29
168
75
93
24.14
7.53
29.33
17.26
1
0 (-0.1,7.6]
Queenstown
4
NaN
4
77
47
30
NaN
NaN
8.51
5.19
2
0 (-0.1,7.6]
Southampton
53
6
59
644
427
217
10.17
2.76
12.41
9.16
3
1 (7.6,7.9]
Queenstown
27
16
43
77
47
30
37.21
53.33
57.45
55.84
4
1 (7.6,7.9]
Southampton
34
10
44
644
427
217
22.73
4.61
7.96
6.83
5
2 (7.9,8]
Cherbourg
4
1
5
168
75
93
20
1.08
5.33
2.98
6
2 (7.9,8]
Southampton
83
13
96
644
427
217
13.54
5.99
19.44
14.91
7
3 (8.0,10.5]
Cherbourg
2
1
3
168
75
93
33.33
1.08
2.67
1.79
8
3 (8.0,10.5]
Queenstown
2
NaN
2
77
47
30
NaN
NaN
4.26
2.6
9
3 (8.0,10.5]
Southampton
56
17
73
644
427
217
23.29
7.83
13.11
11.34
10
4 (10.5,14.5]
Cherbourg
7
8
15
168
75
93
53.33
8.6
9.33
8.93
11
4 (10.5,14.5]
Queenstown
1
2
3
77
47
30
66.67
6.67
2.13
3.9
12
4 (10.5,14.5]
Southampton
40
26
66
644
427
217
39.39
11.98
9.37
10.25
13
5 (14.5,21.7]
Cherbourg
9
10
19
168
75
93
52.63
10.75
12
11.31
14
5 (14.5,21.7]
Queenstown
5
3
8
77
47
30
37.5
10
10.64
10.39
15
5 (14.5,21.7]
Southampton
37
24
61
644
427
217
39.34
11.06
8.67
9.47
16
6 (21.7,27]
Cherbourg
1
4
5
168
75
93
80
4.3
1.33
2.98
17
6 (21.7,27]
Queenstown
2
3
5
77
47
30
60
10
4.26
6.49
18
6 (21.7,27]
Southampton
40
39
79
644
427
217
49.37
17.97
9.37
12.27
19
7 (27.0,39.7]
Cherbourg
14
10
24
168
75
93
41.67
10.75
18.67
14.29
20
7 (27.0,39.7]
Queenstown
5
NaN
5
77
47
30
NaN
NaN
10.64
6.49
21
7 (27.0,39.7]
Southampton
38
24
62
644
427
217
38.71
11.06
8.9
9.63
22
8 (39.7,78]
Cherbourg
5
19
24
168
75
93
79.17
20.43
6.67
14.29
23
8 (39.7,78]
Southampton
37
28
65
644
427
217
43.08
12.9
8.67
10.09
24
9 (78.0,512.3]
Cherbourg
11
33
44
168
75
93
75
35.48
14.67
26.19
25
9 (78.0,512.3]
Queenstown
1
1
2
77
47
30
50
3.33
2.13
2.6
26
9 (78.0,512.3]
Southampton
9
30
39
644
427
217
76.92
13.82
2.11
6.06
27
2 (7.9,8]
Queenstown
NaN
5
5
77
47
30
100
16.67
NaN
6.49
28
9 (78.0,512.3]
Missing
NaN
2
2
2
NaN
2
100
100
NaN
100

dfl2.T is being plotted, but 'survival rate %' is in result. As such, the indices for the values from dfl2.T do not correspond with 'survival rate %'.
Because all of values in result['% total dist by xdim'] are
not unique, we can't use a dict of matched key-values.
Create a corresponding pivoted DataFrame for 'survival rate %', and then flatten it. All of the values will be in the same order as the '% total dist by xdim' values from dfl2.T. As such, they can be indexed.
With respect to dfl2.T, the plot API plots in column order, which means .flatten(order='F') must be used to flatten the array in the correct order to be indexed.
# create a corresponding pivoted dataframe for survival rate %
dfl3 = pd.melt(result, id_vars=[ydim, xdim],value_vars =['survival rate %'], var_name = 'Type',value_name=value_name1).drop(columns='Type')
dfl4 = dfl3.pivot(index=ydim, columns=xdim, values=value_name1)
# flatten dfl4.T in column order
dfl4_flattened = dfl4.T.to_numpy().flatten(order='F')
for i, p in enumerate(ax.patches):
width, height = p.get_width(), p.get_height()
x, y = p.get_xy()
# only print values when height is not 0
if height != 0:
# create the text string
text = f'{height:.0f}%, {dfl4_flattened[i]:.0f}%'
# annotate the bar segments
ax.text(x+width/2, y+height/2, text, horizontalalignment='center', verticalalignment='center')
Notes
Here we can see dfl2.T and dfl4.T
# dfl2.T
fare_ord_grp 0 (-0.1, 7.6] 1 (7.6, 7.9] 2 (7.9, 8.0] 3 (8.0, 10.5] 4 (10.5, 14.5] 5 (14.5, 21.7] 6 (21.7, 27.0] 7 (27.0, 39.7] 8 (39.7, 78.0] 9 (78.0, 512.3]
embark_town
Cherbourg 17.26 NaN 2.98 1.79 8.93 11.31 2.98 14.29 14.29 26.19
Missing NaN NaN NaN NaN NaN NaN NaN NaN NaN 100.00
Queenstown 5.19 55.84 6.49 2.60 3.90 10.39 6.49 6.49 NaN 2.60
Southampton 9.16 6.83 14.91 11.34 10.25 9.47 12.27 9.63 10.09 6.06
# dfl4.T
fare_ord_grp 0 (-0.1, 7.6] 1 (7.6, 7.9] 2 (7.9, 8.0] 3 (8.0, 10.5] 4 (10.5, 14.5] 5 (14.5, 21.7] 6 (21.7, 27.0] 7 (27.0, 39.7] 8 (39.7, 78.0] 9 (78.0, 512.3]
embark_town
Cherbourg 24.14 NaN 20.00 33.33 53.33 52.63 80.00 41.67 79.17 75.00
Missing NaN NaN NaN NaN NaN NaN NaN NaN NaN 100.00
Queenstown NaN 37.21 100.00 NaN 66.67 37.50 60.00 NaN NaN 50.00
Southampton 10.17 22.73 13.54 23.29 39.39 39.34 49.37 38.71 43.08 76.92

Subtracting fix date from whole panda data frame - python

I have data
customer_id purchase_amount date_of_purchase
0 760 25.0 06-11-2009
1 860 50.0 09-28-2012
2 1200 100.0 10-25-2005
3 1420 50.0 09-07-2009
4 1940 70.0 01-25-2013
5 1960 40.0 10-29-2013
6 2620 30.0 09-03-2006
7 3050 50.0 12-04-2007
8 3120 150.0 08-11-2006
9 3260 45.0 10-20-2010
10 3510 35.0 04-05-2013
11 3970 30.0 07-06-2007
12 4000 20.0 11-25-2005
13 4180 20.0 09-22-2010
14 4390 30.0 04-15-2011
15 4750 60.0 02-12-2013
16 4840 30.0 10-14-2005
17 4910 15.0 12-13-2006
18 4950 50.0 05-19-2010
19 4970 30.0 01-12-2006
20 5250 50.0 12-20-2005
Now I want to subtract 01-01-2016 from each row of date_of_purchase
I tried the following so I should have a new column days_since with a number of days.
NOW = pd.to_datetime('01/01/2016').strftime('%m-%d-%Y')
gb = customer_purchases_df.groupby('customer_id')
df2 = gb.agg({'date_of_purchase': lambda x: (NOW - x.max()).days})
any suggestion. how I can achieve this
Thanks in advance

pd.to_datetime(df['date_of_purchase']).rsub(pd.to_datetime('2016-01-01')).dt.days
0 2395
1 1190
2 3720
3 2307
4 1071
5 794
6 3407
7 2950
8 3430
9 1899
10 1001
11 3101
12 3689
13 1927
14 1722
15 1053
16 3731
17 3306
18 2053
19 3641
20 3664
Name: date_of_purchase, dtype: int64

I'm assuming the 'date_of_purchase' column already has the datetime dtype.
>>> df
customer_id purchase_amount date_of_purchase
0 760 25.0 2009-06-11
1 860 50.0 2012-09-28
2 1200 100.0 2005-10-25
>>> df['days_since'] = df['date_of_purchase'].sub(pd.to_datetime('01/01/2016')).dt.days.abs()
>>> df
customer_id purchase_amount date_of_purchase days_since
0 760 25.0 2009-06-11 2395
1 860 50.0 2012-09-28 1190
2 1200 100.0 2005-10-25 3720

Calculate mean of data rows in dataframe with date-headers, dictated by a 'datetime'-column

I have a dataframe with ID's of clients and their expenses for 2014-2018. What I want is to have the mean of the expenses per ID but only the years before a certain date can be taken into account when calculating the mean value (so column 'Date' dictates which columns can be taken into account for the mean).
Example: for index 0 (ID: 12), the date states '2016-03-08', then the mean should be taken from the columns 'y_2014' and 'y_2015', so then for this index, the mean is 111.0.
If the date is too early (e.g. somewhere in 2014 or earlier in this case), then NaN should be returned (see index 6 and 9).
Initial dataframe:
y_2014 y_2015 y_2016 y_2017 y_2018 Date ID
0 100.0 122.0 324 632 NaN 2016-03-08 12
1 120.0 159.0 54 452 541.0 2015-04-09 96
2 NaN 164.0 687 165 245.0 2016-02-15 20
3 180.0 421.0 512 184 953.0 2018-05-01 73
4 110.0 654.0 913 173 103.0 2017-08-04 84
5 130.0 NaN 754 124 207.0 2016-07-03 26
6 170.0 256.0 843 97 806.0 2013-02-04 87
7 140.0 754.0 95 101 541.0 2016-06-08 64
8 80.0 985.0 184 84 90.0 2019-03-05 11
9 96.0 65.0 127 130 421.0 2014-05-14 34
Desired output:
y_2014 y_2015 y_2016 y_2017 y_2018 Date ID mean
0 100.0 122.0 324 632 NaN 2016-03-08 12 111.0
1 120.0 159.0 54 452 541.0 2015-04-09 96 120.0
2 NaN 164.0 687 165 245.0 2016-02-15 20 164.0
3 180.0 421.0 512 184 953.0 2018-05-01 73 324.25
4 110.0 654.0 913 173 103.0 2017-08-04 84 559.0
5 130.0 NaN 754 124 207.0 2016-07-03 26 130.0
6 170.0 256.0 843 97 806.0 2013-02-04 87 NaN
7 140.0 754.0 95 101 541.0 2016-06-08 64 447
8 80.0 985.0 184 84 90.0 2019-03-05 11 284.6
9 96.0 65.0 127 130 421.0 2014-05-14 34 NaN
Tried code: -> I'm still working on it, as I don't really know how to start for this, I only uploaded the dataframe so far, probably something with the 'datetime'-package has to be done to get the desired dataframe?
import pandas as pd
import numpy as np
import datetime
df = pd.DataFrame({"ID": [12,96,20,73,84,26,87,64,11,34],
"y_2014": [100,120,np.nan,180,110,130,170,140,80,96],
"y_2015": [122,159,164,421,654,np.nan,256,754,985,65],
"y_2016": [324,54,687,512,913,754,843,95,184,127],
"y_2017": [632,452,165,184,173,124,97,101,84,130],
"y_2018": [np.nan,541,245,953,103,207,806,541,90,421],
"Date": ['2016-03-08', '2015-04-09', '2016-02-15', '2018-05-01', '2017-08-04',
'2016-07-03', '2013-02-04', '2016-06-08', '2019-03-05', '2014-05-14']})
print(df)

Due to your naming convention, one need to extract the years from column names for comparison purpose. Then you can mask the data and taking mean:
# the years from columns
data = df.filter(like='y_')
data_years = data.columns.str.extract('(\d+)')[0].astype(int)
# the years from Date
years = pd.to_datetime(df.Date).dt.year.values
df['mean'] = data.where(data_years<years[:,None]).mean(1)
Output:
y_2014 y_2015 y_2016 y_2017 y_2018 Date ID mean
0 100.0 122.0 324 632 NaN 2016-03-08 12 111.00
1 120.0 159.0 54 452 541.0 2015-04-09 96 120.00
2 NaN 164.0 687 165 245.0 2016-02-15 20 164.00
3 180.0 421.0 512 184 953.0 2018-05-01 73 324.25
4 110.0 654.0 913 173 103.0 2017-08-04 84 559.00
5 130.0 NaN 754 124 207.0 2016-07-03 26 130.00
6 170.0 256.0 843 97 806.0 2013-02-04 87 NaN
7 140.0 754.0 95 101 541.0 2016-06-08 64 447.00
8 80.0 985.0 184 84 90.0 2019-03-05 11 284.60
9 96.0 65.0 127 130 421.0 2014-05-14 34 NaN

one more answer:
import pandas as pd
import numpy as np

df = pd.DataFrame({"ID": [12,96,20,73,84,26,87,64,11,34],
"y_2014": [100,120,np.nan,180,110,130,170,140,80,96],
"y_2015": [122,159,164,421,654,np.nan,256,754,985,65],
"y_2016": [324,54,687,512,913,754,843,95,184,127],
"y_2017": [632,452,165,184,173,124,97,101,84,130],
"y_2018": [np.nan,541,245,953,103,207,806,541,90,421],
"Date": ['2016-03-08', '2015-04-09', '2016-02-15', '2018-05-01', '2017-08-04',
'2016-07-03', '2013-02-04', '2016-06-08', '2019-03-05', '2014-05-14']})
#Subset from original df to calculate mean
subset = df.loc[:,['y_2014', 'y_2015', 'y_2016', 'y_2017', 'y_2018']]
#an expense value is only available for the calculation of the mean when that year has passed, therefore 2015-01-01 is chosen for the 'y_2014' column in the subset etc. to check with the 'Date'-column
subset.columns = ['2015-01-01', '2016-01-01', '2017-01-01', '2018-01-01', '2019-01-01']

s = subset.columns[0:].values < df.Date.values[:,None]
t = s.astype(float)
t[t == 0] = np.nan
df['mean'] = (subset.iloc[:,0:]*t).mean(1)

print(df)
#Additionally: (gives the sum of expenses before a certain date in the 'Date'-column
df['sum'] = (subset.iloc[:,0:]*t).sum(1)

print(df)

iterating over loc on dataframes

I'm trying to extract data from a list of dataframes and extract row ranges. Each dataframe might not have the same data, therefore I have a list of possible index ranges that I would like loc to loop over, i.e. from the code sample below, I might want CIN to LAN, but on another dataframe, the CIN row doesn't exist, so I will want DET to LAN or HOU to LAN.
so I was thinking putting them in a list and iterating over the list, i.e.
for df in dfs:
ranges=[[df.loc["CIN":"LAN"]], [df.loc["DET":"LAN"]]]
extracted ranges = (i for i in ranges)
I'm not sure how you would iterate over a list and feed into loc, or perhaps .query().
df1 stint g ab r h X2b X3b hr rbi sb cs bb \
year team
2007 CIN 6 379 745 101 203 35 2 36 125.0 10.0 1.0 105
DET 5 301 1062 162 283 54 4 37 144.0 24.0 7.0 97
HOU 4 311 926 109 218 47 6 14 77.0 10.0 4.0 60
LAN 11 413 1021 153 293 61 3 36 154.0 7.0 5.0 114
NYN 13 622 1854 240 509 101 3 61 243.0 22.0 4.0 174
SFN 5 482 1305 198 337 67 6 40 171.0 26.0 7.0 235
TEX 2 198 729 115 200 40 4 28 115.0 21.0 4.0 73
TOR 4 459 1408 187 378 96 2 58 223.0 4.0 2.0 190
df2 so ibb hbp sh sf gidp
year team
2008 DET 176.0 3.0 10.0 4.0 8.0 28.0
HOU 212.0 3.0 9.0 16.0 6.0 17.0
LAN 141.0 8.0 9.0 3.0 8.0 29.0
NYN 310.0 24.0 23.0 18.0 15.0 48.0
SFN 188.0 51.0 8.0 16.0 6.0 41.0
TEX 140.0 4.0 5.0 2.0 8.0 16.0
TOR 265.0 16.0 12.0 4.0 16.0 38.0

Here is a solution:
import pandas as pd
# Prepare a list of ranges
ranges = [('CIN','LAN'), ('DET','LAN')]
# Declare an empty list of data frames and a list with the existing data frames
df_ranges = []
df_list = [df1, df2]
# Loop over multi-indices
for i, idx_range in enumerate(ranges):
df = df_list[i]
row1, row2 = idx_range
df_ranges.append(df.loc[(slice(None), slice(row1, row2)),:])
# Print the extracted data
print('Extracted data:\n')
print(df_ranges)
Output:
[ stint g ab r h X2b X3b hr rbi sb cs bb
year team
2007 CIN 6 379 745 101 203 35 2 36 125 10 1 105
DET 5 301 1062 162 283 54 4 37 144 24 7 97
HOU 4 311 926 109 218 47 6 14 77 10 4 60
LAN 11 413 1021 153 293 61 3 36 154 7 5 114
so ibb hbp sh sf gidp
year team
2008 DET 176 3 10 4 8 28
HOU 212 3 9 16 6 17
LAN 141 8 9 3 8 29]