The post How to Join Multiple Data Frames in R appeared first on Data Science Tutorials

How to Join Multiple Data Frames in R?, you can find it useful to connect many data frames in R. Fortunately, the left join() function from the dplyr package makes this simple to accomplish.

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library(dplyr)

Consider the following three data frames, for instance:

Let’s create a data frame

df1 <- data.frame(Q1 = c('a', 'b', 'c', 'd', 'e', 'f'),
                  Q2 = c(152, 514, 114, 218, 322, 323))
df2 <- data.frame(Q1 = c('a', 'a', 'a', 'b', 'b', 'b'),
                  Q3 = c(523, 324, 233, 134, 237, 141))
df3 <- data.frame(Q1 = c('P1', 'e', 'P2', 'g', 'P5', 'i'),
                  Q4 = c(323, 224, 333, 324, 237, 441))

We can easily conduct two left joins, one after the other, to combine all three data frames.

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connect the three data frames.

df1 %>%
  left_join(df2
, by='Q1') %>%  left_join(df3, by='Q1')
Q1  Q2  Q3  Q4
1   a 152 523  NA
2   a 152 324  NA
3   a 152 233  NA
4   b 514 134  NA
5   b 514 237  NA
6   b 514 141  NA
7   c 114  NA  NA
8   d 218  NA  NA
9   e 322  NA 224
10  f 323  NA  NA

Notably, the outcome of this join can also be saved as a data frame.

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After joining the three data frames, create an extra data frame called alldata and save the outcome.

alldata <- df1 %>%
              left_join(df2, by='Q1') %>%
              left_join(df3, by='Q1')

display the resultant data frame’s summary

glimpse(alldata)
Rows: 10
Columns: 4
$ Q1 <chr> "a", "a", "a", "b", "b", "b", "c", "d", "e", "f"
$ Q2 <dbl> 152, 152, 152, 514, 514, 514, 114, 218, 322, 323
$ Q3 <dbl> 523, 324, 233, 134, 237, 141, NA, NA, NA, NA
$ Q4 <dbl> NA, NA, NA, NA, NA, NA, NA, NA, 224, NA

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