Page 242 - Data Science class 11
P. 242
# Extracting first two rows.
result <- emp.data[1:2,]
print(result)
On execution of the above code, the following result is shown:
Recap
Ÿ Variables are used to store the data, Comments are used to improve code readability, and Keywords are reserved words
that hold a specific meaning to the compiler.
Basic data types in R can be divided into the following types: numeric, integer, complex, character (a.k.a. string) and logical
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(a.k.a. boolean).
A numeric data type is the most common type in R, and contains any number with or without a decimal.
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Integers are numeric data without decimals.
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A complex number is the sum of a real number and an imaginary number.
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Raw data, also known as primary data, are data (e.g., numbers, instrument readings, figures, etc.) collected from a source.
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Ÿ The basic arithmetic operators are: + (addition), - (subtraction), * (multiplication), / (division), ^ (exponentiation) and %%
Modulus.
The command statement is always shown in blue and remarks in green but followed by #.
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A script lets you control the program that you created with coding.
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Variables are nothing but reserved memory locations to store values.
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The variables can be assigned values using the leftward, rightward, and equal to operators.
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In R, a sequence of elements that share the same data type is known as a vector.
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Ÿ There are two types of vectors: Atomic vectors and Lists.
Integer and double vectors are collectively known as numeric vectors.
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Lists are sometimes called recursive vectors because lists can contain other lists.
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When a person writes just one value in R, it becomes a vector of length one and is called a single-element vector.
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When a person writes more than one value in R, it is called a multiple-element vector. We can create a multiple-element
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vector with numeric data using the colon operator.
The return type is determined by the highest type of the components in the hierarchy expression: > list > character >
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complex > double > integer > logical > raw > NULL.
Ÿ A list in R is a type of R object that contains different types of elements like—numbers, vectors, strings, and another list
within it.
Matrices are the R objects in which the elements are arranged in a two-dimensional rectangular layout.
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Arrays are the R data objects in which we can store data in more than two dimensions.
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A data frame is a table or a two-dimensional array-like structure in which each column contains values of one variable and
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each row contains one set of values from each column.
240 Touchpad Data Science-XI

