merge extra rows being added R

Vote count:

0

I have two very large dfs (x= 379638 rows and y[routes] = 4103141 rows). I want to merge y into x, and I do this using every common variable between the two dfs. However, despite me using all the variables I can, my merge code is still adding on an extra 5000 rows (merged df = 384586 rows). My code is the default all.x=FALSE.... so unsure of whats happening here, given that I'm using every variable in each df to merge on. Does anyone know what I'm doing incorrectly?

Below are two mini-samples from my two dfs, (just copy and paste into your console to see) plus my code.

df<-merge(x,routes, by=c('hai_dispense_number', 'hai_age', 'sex', 'date_of_claim', 'quantity', 'hai_ddd', 'hai_strength', 'eligibility_end_date', 'hai_atc'))

First df (x)

x<- read.table(header=T, text=" hai_dispense_number sex hai_age eligibility_end_date quantity date_of_claim hai_atc hai_strength hai_ddd
13   PatientHAI0000092   F      42           2011-02-28        9    2010-06-16 N05BA01         2.00    10.0
14   PatientHAI0000092   F      42           2011-02-28        3    2010-06-16 N05CF02         5.00    10.0
41   PatientHAI0000110   F      31           2011-07-31       10    2010-09-09 N05BA12       250.00     1.0
72   PatientHAI0000360   F      58           2014-10-31       30    2010-04-21 N05CF02        10.00    10.0
82   PatientHAI0000360   F      58           2014-10-31       30    2010-07-19 N05CF02        10.00    10.0
111  PatientHAI0000522   M      38           2012-08-31       10    2010-07-06 N05CF01         7.50     7.5
134  PatientHAI0000731   F      28           2010-12-29        7    2010-06-15 N05CF01         7.50     7.5
137  PatientHAI0000731   F      28           2010-12-29       15    2010-08-18 N05BA12       500.00     1.0
139  PatientHAI0000731   F      29           2012-02-12       42    2010-09-10 N05BA12         0.25     1.0
159  PatientHAI0000798   F      41           2011-08-31       14    2010-06-30 N05CF01         7.50     7.5
") 

second df (routes)

routes<- read.table(header=T, text="hai_dispense_number sex hai_age quantity date_of_claim hai_atc hai_roa hai_strength hai_ddd eligibility_end_date
1   PatientHAI0217603   F      75       14    2010-04-16 N05BA12     O           0.25    1.00           2016-04-30
2   PatientHAI1614296   F      74       30    2010-04-28 N05CD06     O           1.00    1.00           2015-11-30
3   PatientHAI0408690   F      91       28    2010-04-15 N05BA12     O           0.25    1.00           2013-06-30
4   PatientHAI0050917   M      67       56    2010-04-15 N05BE01     O          10.00   30.00           2020-12-31
5   PatientHAI0143945   M      64       30    2010-04-14 N05BA01     O           5.00   10.00           2010-07-31
8   PatientHAI2149890   M      72       84    2010-04-27 N05BA08     O           1.50   10.00           2011-06-30
10  PatientHAI1903034   F      80       45    2010-04-01 N05CD07     O          20.00   20.00           2020-12-31
11  PatientHAI0205229   F      80       56    2010-04-22 N05CD07     O          20.00   20.00           2020-12-31
13  PatientHAI0317751   F      71       30    2010-04-26 N05CD05     O           0.25    0.25           2016-11-30
14  PatientHAI1986979   M      22       15    2010-04-19 N05BA01     O          10.00   10.00           2012-11-30
") 

asked 46 secs ago

user2363642

161