I have the following DataFrame:
data = {'Customer_ID': ['123','2','1010','123'],
'Date_Create': ['12/08/2010','04/10/1998','27/05/2010','12/08/2010'],
'Purchase':[1,1,0,1]
}
df = pd.DataFrame(data, columns = ['Customer_ID', 'Date_Create','Purchase'])
I want to perform this query:
df_2 = df[['Customer_ID','Date_Create','Purchase']].groupby(['Customer_ID'],
as_index=False).sum().sort_values(by='Purchase', ascending=False)
The objective of this query is to sum all purchases(boolean field) and as output a dataframe with 3 columns: 'Customer_ID', 'Date_Create','Purchase
Problem is: the field Date_Create is not in query because it has duplicate as the date_creation of the account does not change.
How can i solve it?
thx
If im understanding it correctly and your source data has some duplicates,
There's a function specifically for this, dataframe.drop_duplicates()
https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.DataFrame.drop_duplicates.html
To only consider some columns in the duplicate check, use subset:
df2 = df.drop_duplicates(subset=['Customer_ID','Date_Create'])
You can add column Date_Create to groupby if same values per Customer_ID:
(df.groupby(['Customer_ID','Date_Create'], as_index=False)['Purchase']
.sum()
.sort_values(by='Purchase', ascending=False))
If not, use some aggregation function - e.g. GroupBy.first for first date per groups:
(df.groupby('Customer_ID')
.agg(Purchase = ('Purchase', 'sum'), Date_Create= ('Date_Create', 'first'))
.reset_index()
.sort_values(by='Purchase', ascending=False))
Related
I have read a csv file and need to find correlation between two columns.
I am using df.stat.corr('Age','Exp') and result is 0.7924058156930612.
But I want to have this result stored in another dataframe with header as "correlation".
correlation
0.7924058156930612
Following up on what #gupta_hemant commented.
You can create a new column as
df.withColumn("correlation", df.stat.corr("Age", "Exp").collect()[0].correlation)
(I am guessing the exact syntax here, but it should be something like this)
After reviewing the code, the syntax should be
import pyspark.sql.functions as F
df.withColumn("correlation", F.lit(df.stat.corr("Age", "Exp")))
Try this and let me know.
corrValue = df.stat.corr("Age", "Exp")
newDF = spark.createDataFrame(
[
(corrValue)
],
["corr"]
)
My current dataframe looks as below:
existing_data = {'STORE_ID': ['1234','5678','9876','3456','6789'],
'FULFILLMENT_TYPE': ['DELIVERY','DRIVE','DELIVERY','DRIVE','DELIVERY'],
'FORECAST_DATE':['2020-08-01','2020-08-02','2020-08-03','2020-08-04','2020-08-05'],
'DAY_OF_WEEK':['SATURDAY','SUNDAY','MONDAY','TUESDAY','WEDNESDAY'],
'START_HOUR':[8,8,6,7,9],
'END_HOUR':[19,19,18,19,17]}
existing = pd.DataFrame(data=existing_data)
I would need the data to be exploded between the start and end hour such that each hour is a different row like below:
needed_data = {'STORE_ID': ['1234','1234','1234','1234','1234'],
'FULFILLMENT_TYPE': ['DELIVERY','DELIVERY','DELIVERY','DELIVERY','DELIVERY'],
'FORECAST_DATE':['2020-08-01','2020-08-01','2020-08-01','2020-08-01','2020-08-01'],
'DAY_OF_WEEK': ['SATURDAY','SATURDAY','SATURDAY','SATURDAY','SATURDAY'],
'HOUR':[8,9,10,11,12]}
required = pd.DataFrame(data=needed_data)
Not sure how to achieve this ..I know it should be with explode() but unable to achieve it.
If small DataFrame or performance is not important use range per both columns with DataFrame.explode:
existing['HOUR'] = existing.apply(lambda x: range(x['START_HOUR'], x['END_HOUR']+1), axis=1)
existing = (existing.explode('HOUR')
.reset_index(drop=True)
.drop(['START_HOUR','END_HOUR'], axis=1))
If performance is important use Index.repeat by subtract both columns and then add counter by GroupBy.cumcount to START_HOUR:
s = existing["END_HOUR"].sub(existing["START_HOUR"]) + 1
df = existing.loc[existing.index.repeat(s)].copy()
add = df.groupby(level=0).cumcount()
df['HOUR'] = df["START_HOUR"].add(add)
df = df.reset_index(drop=True).drop(['START_HOUR','END_HOUR'], axis=1)
I want to map through the rows of df1 and compare those with the values of df2 , by month and day, across every year in df2,leaving only the values in df1 which are larger than those in df2, to add into a new column, 'New'. df1 and df2 are of the same size, and are indexed by 'Month' and 'Day'. what would be the best way to do this?
df1=pd.DataFrame({'Date':['2015-01-01','2015-01-02','2015-01-03','2015-01-``04','2005-01-05'],'Values':[-5.6,-5.6,0,3.9,9.4]})
df1.Date=pd.to_datetime(df1.Date)
df1['Day']=pd.DatetimeIndex(df1['Date']).day
df1['Month']=pd.DatetimeIndex(df1['Date']).month
df1.set_index(['Month','Day'],inplace=True)
df1
df2 = pd.DataFrame({'Date':['2005-01-01','2005-01-02','2005-01-03','2005-01-``04','2005-01-05'],'Values':[-13.3,-12.2,6.7,8.8,15.5]})
df2.Date=pd.to_datetime(df1.Date)
df2['Day']=pd.DatetimeIndex(df2['Date']).day
df2['Month']=pd.DatetimeIndex(df2['Date']).month
df2.set_index(['Month','Day'],inplace=True)
df2
df1 and df2
df2['New']=df2[df2['Values']<df1['Values']]
gives
ValueError: Can only compare identically-labeled Series objects
I have also tried
df2['New']=df2[df2['Values'].apply(lambda x: x < df1['Values'].values)]
The best way to handle your problem is by using numpy as a tool. Numpy has an attribute called "where"that helps a lot in cases like this.
This is how the sentence works:
df1['new column that will contain the comparison results'] = np.where(condition,'value if true','value if false').
First import the library:
import numpy as np
Using the condition provided by you:
df2['New'] = np.where(df2['Values'] > df1['Values'], df2['Values'],'')
So, I think that solves your problem... You can change the value passed to the False condition to every thin you want, this is only an example.
Tell us if it worked!
Let´s try two possible solutions:
The first solution is to sort the index first.
df1.sort_index(inplace=True)
df2.sort_index(inplace=True)
Perform a simple test to see if it works!
df1 == df2
it is possible to raise some kind of error, so if that happens, try this correction instead:
df1.sort_index(inplace=True, axis=1)
df2.sort_index(inplace=True, axis=1)
The second solution is to drop the indexes and reset it:
df1.sort_index(inplace=True)
df2.sort_index(inplace=True)
Perform a simple test to see if it works!
df1 == df2
See if it works and tell us the result.
I have the following pandas dataframe:
import pandas as pd
data = {'Sentences':['Sentence1', 'Sentence2', 'Sentence3', 'Sentences4', 'Sentences5', 'Sentences6','Sentences7', 'Sentences8'],'Time':[1,0,0,1,0,0,1,0]}
df = pd.DataFrame(data)
print(df)
I was wondering how to extract all the "Sentences" according to the "Time" column. I want to gather all the "sentences" from the first "1" to the last "0".
Maybe the expected output explains it better:
[[Sentences1,Sentences2,Sentences3],[Sentences4,Sentences5,Sentences6],[Sentences7,Sentences8]]
Is this somehow possible ? Sorry, I am very new to pandas.
Try this:
s = df['Time'].cumsum()
df.set_index([s, df.groupby(s).cumcount()])['Sentences'].unstack().to_numpy().tolist()
Output:
[['Sentence1', 'Sentence2', 'Sentence3'],
['Sentences4', 'Sentences5', 'Sentences6'],
['Sentences7', 'Sentences8', nan]]
Details:
Use cumsum to group by Time = 1 with following Time = 0.
Next, use groupby with cumcount to increment within each group
Lastly, use set_index and unstack to reshape dataframe.
I'm trying to calculate the average for each column in a dataframe and subtract from each element in the column. I've created a function that attempts to do that, but when I try to implement it using a UDF, I get an error: 'float' object has no attribute 'map'. Any ideas on how I can create such a function? Thanks!
def normalize(data):
average=data.map(lambda x: x[0]).sum()/data.count()
out=data.map(lambda x: (x-average))
return out
mapSTD=udf(normalize,IntegerType())
dats = data.withColumn('Normalized', mapSTD('Fare'))
In your example there is problem with UDF function which can not be applied to row and whole DataFrame. UDF can be applied only to single row, but Spark also enables implementing UDAF (User Defined Aggregate Functions) working on whole DataFrame.
To solve your problem you can use below function:
from pyspark.sql.functions import mean
def normalize(df, column):
average = df.agg(mean(df[column]).alias("mean")).collect()[0]["mean"]
return df.select(df[column] - average)
Use it like this:
normalize(df, "Fare")
Please note that above only works on single column, but it is possible to implement something more generic:
def normalize(df, columns):
selectExpr = []
for column in columns:
average = df.agg(mean(df[column]).alias("mean")).collect()[0]["mean"]
selectExpr.append(df[column] - average)
return df.select(selectExpr)
use it like:
normalize(df, ["col1", "col2"])
This works, but you need to run aggregation for each column, so with many columns performance could be issue, but it is possible to generate only one aggregate expression:
def normalize(df, columns):
aggExpr = []
for column in columns:
aggExpr.append(mean(df[column]).alias(column))
averages = df.agg(*aggExpr).collect()[0]
selectExpr = []
for column in columns:
selectExpr.append(df[column] - averages[column])
return df.select(selectExpr)
Adding onto Piotr's answer. If you need to keep the existing dataframe and add normalized columns with aliases, the function can be modified as:
def normalize(df, columns):
aggExpr = []
for column in columns:
aggExpr.append(mean(df[column]).alias(column))
averages = df.agg(*aggExpr).collect()[0]
selectExpr = ['*']
for column in columns:
selectExpr.append((df[column] - averages[column]).alias('normalized_'+column))
return df.select(selectExpr)