Question

5. The file Minnow Age & Length.xls has the ages and lengths of minnows captured in a local stream. Use R to make a 2 shartSshowing the FREQUENCY distributions of length for the age 1 and age 2 fish. Hint: First, sort the data by age. The age 1 fish are the first series; the age 2 fish are the second series

Age	Length
1	22
1	22
1	23
1	24
1	25
1	25
1	26
1	26
1	27
1	28
1	29
1	29
1	30
1	30
1	30
1	30
1	31
1	31
1	32
1	32
1	33
1	33
1	35
1	35
1	39
1	41
1	42
1	44
2	28
2	29
2	30
2	31
2	32
2	32
2	33
2	34
2	35
2	36
2	38
2	38
2	39
2	39
2	40
2	40
2	41
2	42
2	42
2	42
2	44
2	44
2	45
2	45
2	46
2	48
2	48
2	49
2	50

Answer 1

The first step is to import the excel data into a data frame in R.

For that we make use of the package xlsx.

Before that, we must check the active directory in R by using the code getwd()

It is easier if we place the excel file in this particular location that is returned by the getwd() command.

Now, we load the package by writing the command library("xlsx")

In case we don't have this package, we can install by writing the command install.packages("xlsx") and then write the command library("xlsx") to load the functions in the package.

We import the data by using the read.xlsx function.

The command is: my_data <- read.xlsx("Minnow Age & Length.xlsx",1, header=TRUE)

The arguments are name of the file, sheet number having the data, and TRUE since the first row is the names of the columns (i.e. Age and Length). You can write the command my_data and press enter to print the contents of the data frame and whether or not the import is correct or not.

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Next, we split this data frame into 2 data frames, one for Age 1 and one for Age 2.

The commands are: my_data1 <- subset(my_data,Age==1)

my_data2 <- subset(my_data,Age==2)

Next job is to create the histogram, for which we can use the hist function.

The command is:

hist(my_data1$Length,main="Lengths of Age group 1",xlab="Frequency",ylab="Length",col="Red")

Only hist(my_data1$Length) will work as well but the above adds Title, x and y labels and the Red color to the histogram.

Same command for age group 2 except use the other data frame.

hist(my_data2$Length,main="Lengths of Age group 2",xlab="Frequency",ylab="Length",col="Red")

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The histograms look like:

R R Graphics: Device 2 (ACTIVE) Lengths of Age group 1 On 12 丈 45 40 35 30 25 20 Frequency

R R Graphics: Device 2 (ACTIVE) Lengths of Age group 2 IRD 12 45 50 40 35 30 25 Frequency

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The following shows the commands so far:

>library("xlsx") >my_data <- read.xlsx ("Minnow Age& my_datal <- subset (my_data, Age-l) my_data2 <- subset (my_data,Age--2) of Length.xlsx", 1, header-TRUE) hist (my-datal$Length , main«"Lengths hist (my_data25Length , main="Lengths Age 1", xlab= "Frequency", ylab="Length", col="Red") > group 2",xlab="Frequency" , ylab="Length", col="Red") of Age > group

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Kindly comment in case of any additional clarifications needed. Thanks :)