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| − | ==Assignments and basic operations in '''R'''==
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| − | An assignment is the fact of storing an object under a given name.
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| − | Assignments in '''R''' are done by using the "arrow" (<-) or
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| − | the equal (=) symbol, even though it can be recommended to use the
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| − | arrow because some functions use the equal symbol as an argument.
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| − | Assignments can be done in two directions. Some examples are shown below.
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| − | a <- 2
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| − | b <- 3
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| − | 4 -> c
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| − | a
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| − |
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| − | ## [1] 2
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| − |
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| − | b
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| − | ## [1] 3
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| − |
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| − | c
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| − | ## [1] 4
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| − |
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| − | Operating with objects in '''R''' is very easy. Below some examples with single values:
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| − |
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| − | (a+b)/c*5
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| − |
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| − | ##[1] 6.25
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| − |
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| − | and with vectors.
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| − |
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| − | v.1 <- v*exp((a+b)/c*5)
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| − | v.1
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| − |
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| − | ## [1] 518 1036 1554 2072 2590 3108 3626 4144 4662
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| − | Note that in the first case the calculus was computed and displayed in
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| − | the console, but the result was not assigned to any object. In the
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| − | second case, the result of the calculus was assigned to a new object
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| − | named ''v.1''. In the assignment process it must be considered that
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| − | objects can be overwritten as many times as we want, and the information
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| − | of the original object can be lost if the required attention is not played.
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| − |
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| − | Assignments can also be done to positions in an existent object. In the
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| − | following example, the values in the third column of the data frame ''d'' are replaced by the characters ''low'', ''medium'' and ''high'' as follows:
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| − | d$C <- c("low", "medium", "high")
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| − | d
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| − |
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| − | # A b C
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| − | # 1 1 4 low
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| − | # 2 2 5 medium
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| − | # 3 3 6 high
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| − |
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| − | The assignments can also be to a previously non-existent column in the
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| − | dataframe.
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| − |
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| − | d$E <- m[,3]
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| − | d
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| − |
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| − | # A b C E
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| − | # 1 1 4 low 7
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| − | # 2 2 5 medium 8
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| − | # 3 3 6 high 9
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| − |
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| − | Logical tests can also be done in '''R'''.
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| − |
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| − | e <- c<a
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| − | e
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| − | ## [1] FALSE
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