{ "cells": [ { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" }, "toc": true }, "source": [ "

Table of Contents

\n", "
" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "# Types of Operators" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "Arithmetic Operators `(+ - * / %%` (modulo) `%/%`(integer divide) ` ^`(raised to the power of)) \n", "Relational Operators`(> < <= >= == != )` \n", "Logical Operators `(& | ! && ||)` \n", "Assignment Operators `(<− = <<− -> ->>)` \n", "Miscellaneous Operators `(: %in% %*%)`" ] }, { "cell_type": "raw", "metadata": {}, "source": [ "Arithmetic Operators\n", "\n", "Operator Description Example\n", "- Subtraction 5 - 1 = 4\n", "+ Addition 5 + 1 = 6\n", "* Multiplication 5 * 3 = 15\n", "/ Division 10 / 2 = 5\n", "^ or ** Exponentiation 2*2*2*2*2 as 2 to the power of 5\n", "x%%y Modulus 5%%2 is 1\n", "x%/%y Integer Division 5%/%2 is 2" ] }, { "cell_type": "raw", "metadata": {}, "source": [ "Relational and Logical Operators\n", "\n", "Operator Description Example\n", "< less than 5 < 10\n", "<= less than or equal to <= 5\n", "> greater than 10 > 5\n", ">= greater than or equal to >= 10\n", "== exactly equal to == 10\n", "!= not equal to != 5\n", "!x not x x <- c(5), !x\n", "x | y x or y x <- c(5), y <- c(10), x | y\n", "x & y x and y x <- c(5), y <- c(10), x & y\n", "isTRUE(x) tests whether x is true x <- TRUE, isTRUE(x)\n", " [1] FALSE" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "## Logical AND (`&&`) and Logical OR (`||`)" ] }, { "cell_type": "code", "execution_count": 6, "metadata": { "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] TRUE\n" ] } ], "source": [ "# Called Logical AND operator. Takes first element of both the vectors and gives the TRUE only if both are TRUE.\n", "v <- c(3,0,TRUE,2+2i)\n", "t <- c(1,3,TRUE,2+3i)\n", "print(v&&t)" ] }, { "cell_type": "code", "execution_count": 7, "metadata": { "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] FALSE\n" ] } ], "source": [ "# Called Logical OR operator. Takes first element of both the vectors and gives the TRUE if one of them is TRUE.\n", "v <- c(0,0,TRUE,2+2i)\n", "t <- c(0,3,TRUE,2+3i)\n", "print(v||t)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "## `%in%` Operator" ] }, { "cell_type": "code", "execution_count": 8, "metadata": { "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] TRUE\n", "[1] FALSE\n" ] } ], "source": [ "# This operator is used to identify if an element belongs to a vector.\n", "\n", "v1 <- 8\n", "v2 <- 12\n", "t <- 1:10\n", "print(v1 %in% t) \n", "print(v2 %in% t)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "# Control Structures or Conditional Statements\n", "\n", "(decision making statements)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "![Imgur](https://i.imgur.com/YQfqXlY.png?1)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "### If Condition\n", "**IF statement associates a condition with a sequence of statements, The sequence of statements is executed only if the condition is true. If the condition is false or null, the IF statement does nothing. In either case, control passes to the next statement**" ] }, { "cell_type": "code", "execution_count": 9, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "slide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] \"Num1 is less or equal to Num2\"\n" ] } ], "source": [ "num1=10\n", "num2=20\n", " \n", "if(num1<=num2){\n", "print(\"Num1 is less or equal to Num2\")\n", " }" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "### If..Else" ] }, { "cell_type": "code", "execution_count": 10, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] \"x is less than 10\"\n" ] } ], "source": [ "x <- 1:15\n", "if (sample(x, 1) <= 10) {\n", " print(\"x is less than 10\")\n", "} else {\n", " print(\"x is greater than 10\")\n", "}" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "**Another way in R**" ] }, { "cell_type": "code", "execution_count": 11, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "data": { "text/html": [ "
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"[1] 100\n", "[1] 102.5\n", "[1] 104.5\n" ] } ], "source": [ "x <- head(women,10)\n", "x\n", "mrnull <- NULL\n", "for(i in seq_along(x[,1])){\n", " concat <- c(mrnull, mean(as.numeric(x[i, 1:2])))\n", " print(concat)\n", "}\n" ] }, { "cell_type": "code", "execution_count": 24, "metadata": { "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ ", , 1\n", "\n", " [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]\n", " [1,] 1 2 3 4 5 6 7 8 9 10\n", " [2,] 2 4 6 8 10 12 14 16 18 20\n", " [3,] 3 6 9 12 15 18 21 24 27 30\n", " [4,] 4 8 12 16 20 24 28 32 36 40\n", " [5,] 5 10 15 20 25 30 35 40 45 50\n", " [6,] 6 12 18 24 30 36 42 48 54 60\n", " [7,] 7 14 21 28 35 42 49 56 63 70\n", " [8,] 8 16 24 32 40 48 56 64 72 80\n", " [9,] 9 18 27 36 45 54 63 72 81 90\n", "[10,] 10 20 30 40 50 60 70 80 90 100\n", "\n", ", , 2\n", "\n", " [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]\n", " [1,] 2 4 6 8 10 12 14 16 18 20\n", " [2,] 4 8 12 16 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[4,] 44 88 132 176 220 264 308 352 396 440\n", " [5,] 55 110 165 220 275 330 385 440 495 550\n", " [6,] 66 132 198 264 330 396 462 528 594 660\n", " [7,] 77 154 231 308 385 462 539 616 693 770\n", " [8,] 88 176 264 352 440 528 616 704 792 880\n", " [9,] 99 198 297 396 495 594 693 792 891 990\n", "[10,] 110 220 330 440 550 660 770 880 990 1100\n", "\n", ", , 12\n", "\n", " [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]\n", " [1,] 12 24 36 48 60 72 84 96 108 120\n", " [2,] 24 48 72 96 120 144 168 192 216 240\n", " [3,] 36 72 108 144 180 216 252 288 324 360\n", " [4,] 48 96 144 192 240 288 336 384 432 480\n", " [5,] 60 120 180 240 300 360 420 480 540 600\n", " [6,] 72 144 216 288 360 432 504 576 648 720\n", " [7,] 84 168 252 336 420 504 588 672 756 840\n", " [8,] 96 192 288 384 480 576 672 768 864 960\n", " [9,] 108 216 324 432 540 648 756 864 972 1080\n", "[10,] 120 240 360 480 600 720 840 960 1080 1200\n", "\n", ", , 13\n", "\n", " [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]\n", " [1,] 13 26 39 52 65 78 91 104 117 130\n", " [2,] 26 52 78 104 130 156 182 208 234 260\n", " [3,] 39 78 117 156 195 234 273 312 351 390\n", " [4,] 52 104 156 208 260 312 364 416 468 520\n", " [5,] 65 130 195 260 325 390 455 520 585 650\n", " [6,] 78 156 234 312 390 468 546 624 702 780\n", " [7,] 91 182 273 364 455 546 637 728 819 910\n", " [8,] 104 208 312 416 520 624 728 832 936 1040\n", " [9,] 117 234 351 468 585 702 819 936 1053 1170\n", "[10,] 130 260 390 520 650 780 910 1040 1170 1300\n", "\n", ", , 14\n", "\n", " [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]\n", " [1,] 14 28 42 56 70 84 98 112 126 140\n", " [2,] 28 56 84 112 140 168 196 224 252 280\n", " [3,] 42 84 126 168 210 252 294 336 378 420\n", " [4,] 56 112 168 224 280 336 392 448 504 560\n", " [5,] 70 140 210 280 350 420 490 560 630 700\n", " [6,] 84 168 252 336 420 504 588 672 756 840\n", " [7,] 98 196 294 392 490 588 686 784 882 980\n", " [8,] 112 224 336 448 560 672 784 896 1008 1120\n", " [9,] 126 252 378 504 630 756 882 1008 1134 1260\n", "[10,] 140 280 420 560 700 840 980 1120 1260 1400\n", "\n", ", , 15\n", "\n", " [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]\n", " [1,] 15 30 45 60 75 90 105 120 135 150\n", " [2,] 30 60 90 120 150 180 210 240 270 300\n", " [3,] 45 90 135 180 225 270 315 360 405 450\n", " [4,] 60 120 180 240 300 360 420 480 540 600\n", " [5,] 75 150 225 300 375 450 525 600 675 750\n", " [6,] 90 180 270 360 450 540 630 720 810 900\n", " [7,] 105 210 315 420 525 630 735 840 945 1050\n", " [8,] 120 240 360 480 600 720 840 960 1080 1200\n", " [9,] 135 270 405 540 675 810 945 1080 1215 1350\n", "[10,] 150 300 450 600 750 900 1050 1200 1350 1500\n", "\n" ] } ], "source": [ "# Create your three-dimensional array\n", "my_array <- array(1:20, dim=c(20, 20, 20))\n", "\n", "for (i in 1:dim(my_array)[1]) {\n", " for (j in 1:dim(my_array)[2]) {\n", " for (k in 1:dim(my_array)[3]) {\n", " my_array[i,j,k] = i*j*k\n", " }\n", " }\n", "}\n", "\n", "# Show a 10x10x15 chunk of your array\n", "print(my_array[1:10, 1:10, 1:15])" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "### While Loop\n", "Loop until a specific condition is met" ] }, { "cell_type": "code", "execution_count": 25, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] 1\n", "[1] 2\n", "[1] 3\n", "[1] 4\n", "[1] 5\n" ] } ], "source": [ "i <- 1\n", "\n", "while (i < 6) {\n", " print(i)\n", " i = i+1\n", "}" ] }, { "cell_type": "code", "execution_count": 26, "metadata": { "scrolled": true, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] 0\n", "[1] 1\n", "[1] 1\n", "[1] 2\n", "[1] 3\n", "[1] 5\n", "[1] 8\n", "[1] 13\n", "[1] 21\n", "[1] 34\n" ] } ], "source": [ "a <- 0\n", "b <- 1\n", "print(a)\n", "while (b < 50) {\n", " print(b)\n", " temp <- a + b\n", " a <- b\n", " b <- temp\n", "}" ] }, { "cell_type": "code", "execution_count": 27, "metadata": { "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] 0\n", "[1] 1\n", "[1] 1\n", "[1] 2\n", "[1] 3\n", "[1] 5\n", "[1] 8\n", "[1] 13\n", "[1] 21\n", "[1] 34\n" ] } ], "source": [ "a <- 0\n", "b <- 1\n", "print(a)\n", "while (b < 50) {\n", " print(b)\n", " temp <- a + b\n", " a <- b\n", " b <- temp\n", "}" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "## repeat, break, next and switch" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "### Repeat statement\n", "Iterate over a block of code multiple number of times." ] }, { "cell_type": "code", "execution_count": 28, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] 1\n", "[1] 2\n", "[1] 3\n", "[1] 4\n", "[1] 5\n" ] } ], "source": [ "x <- 1\n", "\n", "repeat {\n", " print(x)\n", " x = x+1\n", " if (x == 6){\n", " break\n", " }\n", "}" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "### Break Statement\n", "break is used inside any loop like `repeat`, `for` or `while` to stop the iterations and flow the control outside of the loop." ] }, { "cell_type": "code", "execution_count": 29, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] 1\n", "[1] 2\n" ] } ], "source": [ "x <- 1:5\n", "\n", "for (val in x) {\n", " if (val == 3){\n", " break\n", " }\n", " print(val)\n", "}" ] }, { "cell_type": "code", "execution_count": 30, "metadata": { "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] \"1 and so on. \"\n", "[1] \"2 and so on. \"\n", "[1] \"3 and so on. \"\n", "[1] \"4 and so on. \"\n", "[1] \"5 and so on. \"\n" ] } ], "source": [ "x <- 1:10\n", "for (num in x){\n", " if (num==6) break\n", " mynum <- paste(num, \"and so on. \", sep = \" \")\n", " print(mynum)\n", "}" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "### Next Statment\n", "* Useful to controls the flow of R loops \n", "* generaal usage inside the For Loop and While Loop " ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "**Example:**" ] }, { "cell_type": "code", "execution_count": 31, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] 1\n", "[1] 2\n", "[1] 4\n", "[1] 5\n" ] } ], "source": [ "x <- 1:5\n", "\n", "for (val in x) {\n", " if (val == 3){\n", " next\n", " }\n", " print(val)\n", "}" ] }, { "cell_type": "code", "execution_count": 32, "metadata": { "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "data": { "text/html": [ "
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Each value is called a case** \n", "\n", "Syntax:\n", "```r\n", "switch (Expression, \"Option 1\", \"Option 2\", \"Option 3\", ....., \"Option N\") \n", "```" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "subslide" } }, "source": [ "**Examples:**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "* If the value evaluated is a number, that item of the list is returned." ] }, { "cell_type": "code", "execution_count": 15, "metadata": {}, "outputs": [ { "data": { "text/html": [ "'green'" ], "text/latex": [ "'green'" ], "text/markdown": [ "'green'" ], "text/plain": [ "[1] \"green\"" ] }, "metadata": {}, "output_type": "display_data" }, { "data": { "text/html": [ "'red'" ], "text/latex": [ "'red'" ], "text/markdown": [ "'red'" ], "text/plain": [ "[1] \"red\"" ] }, "metadata": {}, "output_type": "display_data" }, { "data": { "text/html": [ "'cloth'" ], "text/latex": [ "'cloth'" ], "text/markdown": [ "'cloth'" ], "text/plain": [ "[1] \"cloth\"" ] }, "metadata": {}, "output_type": "display_data" }, { "data": { "text/plain": [ "NULL" ] }, "metadata": {}, "output_type": "display_data" }, { "data": { "text/plain": [ "NULL" ] }, "metadata": {}, "output_type": "display_data" } ], "source": [ "switch(2,\"red\",\"green\",\"blue\")\n", "# [1] \"green\"\n", "switch(1,\"red\",\"green\",\"blue\")\n", "# [1] \"red\"\n", "################\n", "x <- \"red\"\n", "switch(x, red=\"cloth\", size=5, name=\"table\")\n", "#################\n", "# If the numeric value is out of range (greater than the number of items in the list or smaller than 1), then, \n", "# NULL is returned.\n", " x <- switch(4,\"red\",\"green\",\"blue\")\n", " x\n", " x <- switch(0,\"red\",\"green\",\"blue\")\n", " x" ] }, { "cell_type": "code", "execution_count": 35, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "Please enter any ARITHMETIC OPERATOR You wish!: -\n", "[1] \"Subtraction of two numbers is: 10\"\n" ] } ], "source": [ "number1 <- 30\n", "number2 <- 20\n", "operator <- readline(prompt=\"Please enter any ARITHMETIC OPERATOR You wish!: \")\n", " \n", "switch(operator,\n", " \"+\" = print(paste(\"Addition of two numbers is: \", number1 + number2)),\n", " \"-\" = print(paste(\"Subtraction of two numbers is: \", number1 - number2)),\n", " \"*\" = print(paste(\"Multiplication of two numbers is: \", number1 * number2)),\n", " \"^\" = print(paste(\"Exponent of two numbers is: \", number1 ^ number2)),\n", " \"/\" = print(paste(\"Division of two numbers is: \", number1 / number2)),\n", " \"%/%\" = print(paste(\"Integer Division of two numbers is: \", number1 %/% number2)),\n", " \"%%\" = print(paste(\"Division of two numbers is: \", number1 %% number2))\n", ")" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "**Conclusion**\n", "\n", "**Loops are not recommended until and unless its really needed, since R has vectorisation feature**" ] }, { "cell_type": "code", "execution_count": 36, "metadata": { "run_control": { "frozen": false, "read_only": false }, "slideshow": { "slide_type": "subslide" } }, "outputs": [ { "name": "stdout", "output_type": "stream", "text": [ "[1] 5 10 15 20 25 30 35 45\n", "[1] 6 7 8 9 10 11 12 14\n", "[1] -4 -3 -2 -1 0 1 2 4\n" ] } ], "source": [ "# let us take a vector \n", "vect <- c(1,2,3,4,5,6,7,9)\n", "# now we multiply each element of vect with 5\n", "print(vect * 5)\n", "# now we add each element of vect with 5\n", "print(vect + 5)\n", "# now we subtract each element of vect with 5\n", "print(vect - 5)" ] }, { "cell_type": "markdown", "metadata": { "slideshow": { "slide_type": "slide" } }, "source": [ "# Vectorization and recycling concepts" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "**Vectorized Operations**" ] }, { "cell_type": "markdown", "metadata": {}, "source": [ "* when you apply a function to a vector, it applies the function to every element of the vector.\n", "* All the mathematical operators, like +, -, *, and the logical operators, like & (AND), | (OR), and the comparison operators, like < and > are hungry to operate element-wise on every element of a vector." ] }, { "cell_type": "code", "execution_count": null, "metadata": {}, "outputs": [], "source": [ "For example, to add pairs of numbers contained in two vectors" ] }, { "cell_type": "code", "execution_count": 16, "metadata": {}, "outputs": [ { "data": { "text/html": [ "
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xy
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