How can I export a large list from R to Matlab

Hi all,

I have created a large list in R and now, I intend to use this list in matlab. Can anyone help me in this regard?

[Behrooz Daneshian]

The elements of the list are all tibble.

[Rik]

Can you provide a small example of the input and the intended output? That would also explain what a tibble would be.

[Behrooz Daneshian]

Would you please see the attached jpgs? the daily_t is showing the created list that each element of this list is a data frame(or tibble). I think tibble in R is the same data structure as table. tibble jpg represents each element of list " daily_t.

Answer 1

[Shushant]

Hi @Behrooz Daneshian,

I understand you are trying to convert a list of Data Frame from R (as shown in the image "daily_t.JPG") to a table in MATLAB (as shown in the image tibble.JPG). I am assuming the fact that the list of data frames in R all have 3 common columns which are 'id', 'date' and 'TAVG' with different rows, and you want to get this data as a single table in MATLAB with 3 columns and all the rows. To achieve this, I have also created a small list of data frame in r as shown below.

Code for R:

#Create data frame with 2 rows and 3 columns 
df1 = data.frame(
id = c('CA0012303','CA0012305'),
date = c("2007-06-22", "2007-06-26"),
TAVG = c(-0.85, 3.65)
)

# Create another data frame with 3 rows and the same 3 columns
df2 = data.frame(
id = c('CA003303', 'CA001533', 'CA556632'),
date = c("2007-07-22", "2007-07-24", "2006-07-24"),
TAVG = c(7.7, 7.86, 3.5)
)

# Create list of data frame using list()
listOfDataframe = list(df1, df2)
print(listOfDataframe)

Output:

[[1]]

id date TAVG

1 CA0012303 2007-06-22 -0.85

2 CA0012305 2007-06-26 3.65

[[2]]

id date TAVG

1 CA003303 2007-07-22 7.70

2 CA001533 2007-07-24 7.86

3 CA556632 2006-07-24 3.50

Now, I used the "bind_rows" function from the "dplyr" library to bind the list of data frames and convert them into one dataframe.

Code for R:

# Installing and importing the dplyr package
install.packages("dplyr")
library("dplyr")
# Combining the data frames
finalDset = bind_rows( listOfDataframe)
print(finalDset)

Output:

id date TAVG

1 CA0012303 2007-06-22 -0.85

2 CA0012305 2007-06-26 3.65

3 CA003303 2007-07-22 7.70

4 CA001533 2007-07-24 7.86

5 CA556632 2006-07-24 3.50

The final step in R is to export the "finalDset" as a MAT file to accomplish this we use the function "writeMat" from the library "R.matlab".

Code for R:

# installing and importing the R.matlab package

install.packages(c('R.matlab'), repos='http://cran.us.r-project.org')

library(R.matlab)

writeMat(con="myMat.mat", myTable = finalDset)

This will create a new MAT file called "myMat.mat" in your current working directory. Copy that file into your MATLAB working directory and load the file to your workspace. Once, loaded we will see a new variable called "myTable" created in our Workspace with the datatype as struct. We will then convert "myTable" to a table using the function "struct2table". Finally, we will convert the "id" and "date" from cell to string to get the desired result as shown in image "tibble.JPG"

Code for MATLAB with outputs:

>> load("myMat.mat")
>> myTable

myTable =

struct with fields:

id: {5×1 cell}

date: {5×1 cell}

TAVG: [5×1 double]

>> myTable = struct2table(myTable)

myTable =

5×3 table

id date TAVG

_____________ ______________ _____

{'CA0012303'} {'2007-06-22'} -0.85

{'CA0012305'} {'2007-06-26'} 3.65

{'CA003303' } {'2007-07-22'} 7.7

{'CA001533' } {'2007-07-24'} 7.86

{'CA556632' } {'2006-07-24'} 3.5

>> myTable.id = char(myTable.id)

myTable =

5×3 table

id date TAVG

_________ ______________ _____

CA0012303 {'2007-06-22'} -0.85

CA0012305 {'2007-06-26'} 3.65

CA003303 {'2007-07-22'} 7.7

CA001533 {'2007-07-24'} 7.86

CA556632 {'2006-07-24'} 3.5

>> myTable.date = char(myTable.date)

myTable =

5×3 table

id date TAVG

_________ __________ _____

CA0012303 2007-06-22 -0.85

CA0012305 2007-06-26 3.65

CA003303 2007-07-22 7.7

CA001533 2007-07-24 7.86

CA556632 2006-07-24 3.5

[Heath]

That's a bold assumption