Plot columns from list of dataframes in R

In this article, we will discuss how to plot columns from a list of dataframes in R programming language. 

Note: We are taking a line plot for implementation same can be applied to any other plot.

The ggplot() method is supplemented by different geometrical shapes to indicate the type of data plotting. The geom_line() method is used to plot the data in the form of lines. 

Syntax:

geom_line()

We will be using the lapply() method in base R which applies a function, which may be user defined or pre-defined to the input data object. 

Syntax:

lapply(list-of-data-frame, FUN)

Parameter : 

• list-of-data-frame – The list of dataframes formed.
• FUN – The FUN here is the ggplot() method along with the mappings and geometrical plot visualizations to be used.

Let’s move to implementation, to understand the concept better.

Example 1: Plot columns from a list of two dataframes

R

library("ggplot2")

# create first dataframe
data_frame1<-data.frame(col1=c(rep('Jan2021',5),
                               rep('Feb2021',5),
                               rep('Mar2021',5)),
                col2=rnorm(15),
                col3=rep(1:5,3)
                )

# create second dataframe
data_frame2<-data.frame(col1=c(rep('Jan2021',5),
                               rep('Feb2021',5),
                               rep('Mar2021',5)),
                 col2=rnorm(15),
                 col3=rep(1:5,3)
                 )

# creating list of dataframes
data_frames<-list(data_frame1, data_frame2)

graph<-lapply(data_frames,function(x)
  p<-ggplot(x,aes(x= col3,y= col2,color=factor(col1),
                  group=factor(col1))) +
    geom_line() +
    facet_wrap(~col1)
)
print (graph)

Output

Example 2: Example to show usage of three dataframes to form the list 

R

library("ggplot2")

# create first dataframe
data_frame1<-data.frame(col1=c(rep('Grp1',2),rep('Grp2',2),rep('Grp3',2)),
                col2=rep(letters[1:3],2),
                col3=rep(1:2,3)
                )

# create second dataframe
data_frame2<-data.frame(col1=c(rep('Grp1',2),rep('Grp2',2),rep('Grp3',2)),
                        col2=rep(letters[1:3],2),
                        col3=rep(1:2,3)
)

# creating list of dataframes
data_frames<-list(data_frame1, data_frame2)

graph<-lapply(data_frames,
              function(x)
                p<-ggplot(x,aes(x= col3,y= col2,color=factor(col1),
                                group=factor(col1))) +
                geom_line() +
                facet_wrap(~col1)
)

print (graph)

Output

Example 3: plotting different types of dataframes 

R

library("ggplot2")

# create first dataframe
data_frame1<-data.frame(col1=c(rep('Jan2021',5),rep('Feb2021',5),rep('Mar2021',5)),
                        col2=rnorm(15),
                        col3=rep(1:5,3)
)

# create second dataframe
data_frame2<-data.frame(col1=c(rep('Grp1',2),rep('Grp2',2),rep('Grp3',2)),
                        col2=rep(letters[1:3],2),
                        col3=rep(1:2,3)
)

# creating list of dataframes
df<-list(data_frame1, data_frame2)

graph<-lapply(df,
              function(x)
                p<-ggplot(x,aes(x= col3,y= col2,color=factor(col1),
                                group=factor(col1))) +
                geom_line() +
                facet_wrap(~col1)
)
print (graph)

Output