How to replace value of r's dataframe column with other dataframe column

Question

I have following data frame in R

Amount   Transaction_Type
62.81          1
6.66           2
19.9           3
24.02          2
24.02          2
45.2           1
19.76          3

The other dataframe I have is following

Transaction        Transaction_Type   
  CARD                    1
  CASH                    2
  VOUCHER                 3

I want to replace Transaction values in the first dataframe,so it will look like following

Amount      Transaction_Type
62.81          CARD
6.66           CASH
19.9           VOUCHER
24.02          CASH
24.02          CASH
45.2           CARD
19.76          VOUCHER

Please help.

Why not simply df1$Transaction_Type <- df2[match(df1$Transaction_Type, df2$Transaction_Type), 1] ? — Steven Beaupré
– Steven Beaupré, Commented Jul 30, 2016 at 12:39

Nikos · Accepted Answer · 2016-07-30 10:26:27Z

2

This is easy to do using the merge method of R. In your example:

a=data.frame(
   "Amount"=c(62.81,6.66,19.9,24.02,24.02,45.2,19.76),
   "Transaction_Type"=c(1,2,3,2,2,1,3))
t=data.frame(
   "Transaction"=c("CARD","CASH","VOUCHER"),
   "Transaction_Type"=c(1,2,3))

if you run the following: merge(a,t,by="Transaction_Type") you will output the structure you want:

  Transaction_Type Amount Transaction
1                1  62.81        CARD
2                1  45.20        CARD
3                2   6.66        CASH
4                2  24.02        CASH
5                2  24.02        CASH
6                3  19.90     VOUCHER
7                3  19.76     VOUCHER

Of course afterwards, you can keep the columns you want.

Hope this helps.

answered Jul 30, 2016 at 10:26

Nikos

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Comments

akrun · Accepted Answer · 2016-07-30 13:11:53Z

1

We can use match from base R

df1$Transaction_Type <- df2$Transaction[match(df1$Transaction_Type, 
                                df2$Transaction_Type)]
df1$Transaction_Type
#[1] "CARD"    "CASH"    "VOUCHER" "CASH"    "CASH"    "CARD"    "VOUCHER"

Or another base R option is

unname(with(df2, setNames(Transaction, Transaction_Type))[as.character(df1$Transaction_Type)])
#[1] "CARD"    "CASH"    "VOUCHER" "CASH"    "CASH"    "CARD"    "VOUCHER"

edited Jul 30, 2016 at 13:11

answered Jul 30, 2016 at 12:42

akrun

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Sumedh · Accepted Answer · 2016-07-30 10:27:23Z

1

Assuming the first dataframe is df1, and the second is df2:

library(dplyr)

left_join(df1, df2, by = "Transaction_Type") %>% select(-Transaction_Type)

#  Amount Transaction
#1  62.81        CARD
#2   6.66        CASH
#3  19.90     VOUCHER
#4  24.02        CASH
#5  24.02        CASH
#6  45.20        CARD
#7  19.76     VOUCHER

answered Jul 30, 2016 at 10:27

Sumedh

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