Add iterations over multiple lists and 'lag_list' function

DESCRIPTION

@@ -1,7 +1,7 @@
 Package: comprehenr
 Type: Package
 Title: List Comprehensions
-Version: 0.5.4
+Version: 0.6.0
 Maintainer: Gregory Demin <gdemin@gmail.com>
 Authors@R: person("Gregory", "Demin", email = "gdemin@gmail.com",
          role = c("aut", "cre"))

NAMESPACE

@@ -1,6 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
 export(enumerate)
+export(lag_list)
 export(mark)
 export(numerate)
 export(to_list)

NEWS

@@ -1,3 +1,8 @@
+0.6.0 (18.03.2019)
+================
+* add iterations over multiple lists: to_vec(for(`i, j` in numerate(letters)) if(i %% 2==0) paste(i, j))
+* add function 'lag_list':  x -> list(x[i-1], x[i])
+
 0.5.4 (06.03.2019)
 ================
 * Initial release

R/numerate.R

@@ -8,9 +8,10 @@
 #' \code{unmark}.}
 #' \item{zip_lists}{ combine lists side-by-sidy. Reverse operation - \code{unzip_list}.}
 #' \item{unzip_list}{ It's similair to matrix transposition but for list of lists.}
+#' \item{lag_list}{ convert argument to list of arguments with previous values. x -> list(x[i-1], x[i]).}
 #' }
 #'
-#' @param x list or list of lists
+#' @param x list, vector or list of lists
 #' @param item numeric number of list in which stored values
 #' @param ... lists which will be zipped
 #'
@@ -30,6 +31,10 @@
 #' named_list = c('Chicago' = 'ORD', 'Detroit' = 'DTW', 'Atlanta' = 'ATL')
 #' str(mark(named_list))
 #'
+#' set.seed(123)
+#' rand_sequence = runif(20)
+#' # gives only locally increasing values
+#' to_vec(for(`i, j` in lag_list(rand_sequence)) if(j>i) j)
 numerate = function(x){
     unzip_list(list(seq_along(x), x))
 }
@@ -94,6 +99,12 @@ zip_lists = function(...){
     unzip_list(list(...))
 }
 
+#' @export
+#' @rdname numerate
+lag_list = function(x){
+    lapply(seq_along(x)[-1], function(i) list(x[i-1], x[i]))
+}
+
 
 set_names = function (object = nm, nm) {
     names(object) = nm

R/to_list.R

@@ -2,7 +2,8 @@
 #'
 #' \code{to_list} converts usual R loops expressions to list producers.
 #' Expression should be started with \code{for} ,  \code{while} or
-#' \code{repeat}. See examples.
+#' \code{repeat}. You can iterate over multiple lists if you provide several
+#' loop variables in backticks. See examples.
 #' @param expr expression which starts with \code{for} ,  \code{while} or \code{repeat}.
 #' @param recursive	logical. Should unlisting be applied to list components of result? See \link[base]{unlist} for details.
 #' @param use.names logical. Should names be preserved? See \link[base]{unlist} for details.
@@ -24,12 +25,21 @@
 #' noprimes = to_vec(for (i in 2:7) for (j in seq(i*2, 99, i)) j)
 #' primes = to_vec(for (x in 2:99) if(!x %in% noprimes) x)
 #' primes
+#'
+#' # iteration over multiple lists
+#' to_vec(for(`i, j` in numerate(letters)) if(i %% 2==0) paste(i, j))
+#'
+#' set.seed(123)
+#' rand_sequence = runif(20)
+#' # gives only locally increasing values
+#' to_vec(for(`i, j` in lag_list(rand_sequence)) if(j>i) j)
 to_list = function(expr){
     expr = substitute(expr)
     if(!is_loop(expr)) {
         stop(paste("argument should be expression with 'for', 'while' or 'repeat' but we have: ", deparse(expr, width.cutoff = 500)[1]))
     }
 
+    expr = expand_loop_variables(expr)
     expr = add_assignment_to_final_loops(expr)
     on.exit(suppressWarnings(rm(list = c(".___res", ".___counter", ".__curr"), envir = parent.frame())))
     eval.parent(quote(.___res <- list()))
@@ -63,12 +73,48 @@ add_assignment_to_final_loops = function(expr){
     expr
 }
 
+expand_loop_variables = function(expr){
+    if(!is.call(expr)) return(expr)
+    if(is_for_loop(expr)){
+            expr = add_expansion_to_loop(expr)
+            expr[-1] = as.call(lapply(as.list(expr)[-1], expand_loop_variables))
+    } else {
+        expr = as.call(lapply(as.list(expr), expand_loop_variables))
+    }
+    expr
+}
+
+add_expansion_to_loop = function(expr){
+
+    loop_variable = expr[[2]]
+    if(is.symbol(loop_variable) && grepl(",", as.character(loop_variable))){
+        all_loop_variables = trimws(unlist(strsplit(as.character(loop_variable), split = ",")))
+        expansion_expr = lapply(seq_along(all_loop_variables), function(item_num){
+            curr_item = as.name(all_loop_variables[item_num])
+            bquote(.(curr_item) <- .(loop_variable)[[.(item_num)]])
+        })
+        expansion_expr = as.call(c(list(quote(`{`)), expansion_expr))
+        last_item = length(expr)
+        expr[[last_item]] = bquote({
+            .(expansion_expr)
+            .(expr[[last_item]])
+        })
+    }
+    expr
+}
+
 is_loop = function(expr){
     if(!is.call(expr)) return(FALSE)
     first_item = expr[[1]]
     identical(first_item, quote(`for`)) ||identical(first_item, quote(`while`)) ||identical(first_item, quote(`repeat`))
 }
 
+is_for_loop = function(expr){
+    if(!is.call(expr)) return(FALSE)
+    first_item = expr[[1]]
+    identical(first_item, quote(`for`))
+}
+
 has_loop_inside = function(expr){
     if(!is.call(expr)) return(FALSE)
     if(is_loop(expr)) return(TRUE)

README.md

@@ -26,3 +26,13 @@ noprimes = to_vec(for (i in 2:7) for (j in seq(i*2, 99, i)) j)
 primes = to_vec(for (x in 2:99) if(!x %in% noprimes) x)
 primes
 ```
+You can iterate over multiple lists if you provide several loop variables in backticks:
+```R
+to_vec(for(`i, j` in numerate(letters)) if(i %% 2==0) paste(i, j))
+
+set.seed(123)
+rand_sequence = runif(20)
+# gives only locally increasing values
+to_vec(for(`i, j` in lag_list(rand_sequence)) if(j>i) j)
+
+```

tests/testthat/test_numerate.R

@@ -123,3 +123,14 @@ expect_error(
         )
     )
 )
+
+
+
+expect_equal(
+    lag_list(1:3),
+    list(
+        list(1,2),
+        list(2,3)
+    )
+
+)

tests/testthat/test_to_list.R

@@ -99,3 +99,21 @@ expect_equal(
     to_vec(for(i in colnames(iris)) if(is.numeric(iris[[i]])) setNames(mean(iris[[i]]), i) , use.names = TRUE),
     colMeans(iris[,-5])
 )
+
+
+context("`i, j`")
+
+res = to_vec(for(`i, j` in zip_lists(letters, LETTERS)) paste(i, j))
+expect_identical(res, paste(letters, LETTERS))
+
+
+res = to_vec(for(`i, j` in numerate(letters)) if(i %% 2==0) paste(i, j))
+index = seq_along(letters)
+expect_identical(res, paste(index[index %% 2==0], letters[index %% 2==0]))
+
+
+res = to_vec(for(`i, j` in numerate(letters)) if(i %% 2==0) for(`k, z` in numerate(LETTERS)) paste(i, j, k, z))
+index = seq_along(letters)
+true_res = expand.grid(paste(seq_along(letters), LETTERS), paste(index[index %% 2==0], letters[index %% 2==0]))
+true_res = paste(true_res[[2]], true_res[[1]])
+expect_identical(res, true_res)

vignettes/Introduction.R

@@ -21,3 +21,12 @@ noprimes = to_vec(for (i in 2:7) for (j in seq(i*2, 99, i)) j)
 primes = to_vec(for (x in 2:99) if(!x %in% noprimes) x)
 primes
 
+## ------------------------------------------------------------------------
+to_vec(for(`i, j` in numerate(letters)) if(i %% 2==0) paste(i, j))
+
+set.seed(123)
+rand_sequence = runif(20)
+# gives only locally increasing values
+to_vec(for(`i, j` in lag_list(rand_sequence)) if(j>i) j)
+
+

vignettes/Introduction.html

@@ -12,7 +12,7 @@
 
 
 
-<title>List comprehensions in R</title>
+<title>List Comprehensions in R</title>
 
 
 
@@ -296,7 +296,7 @@
 
 
 
-<h1 class="title toc-ignore">List comprehensions in R</h1>
+<h1 class="title toc-ignore">List Comprehensions in R</h1>
 
 
 
@@ -338,6 +338,17 @@ <h1 class="title toc-ignore">List comprehensions in R</h1>
 <a class="sourceLine" id="cb3-11" data-line-number="11">primes</a>
 <a class="sourceLine" id="cb3-12" data-line-number="12"><span class="co">#&gt;  [1]  2  3  5  7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83</span></a>
 <a class="sourceLine" id="cb3-13" data-line-number="13"><span class="co">#&gt; [24] 89 97</span></a></code></pre></div>
+<p>You can iterate over multiple lists if you provide several loop variables in backticks:</p>
+<div class="sourceCode" id="cb4"><pre class="sourceCode r"><code class="sourceCode r"><a class="sourceLine" id="cb4-1" data-line-number="1"><span class="kw">to_vec</span>(<span class="cf">for</span>(<span class="st">`</span><span class="dt">i, j</span><span class="st">`</span> <span class="cf">in</span> <span class="kw">numerate</span>(letters)) <span class="cf">if</span>(i <span class="op">%%</span><span class="st"> </span><span class="dv">2</span><span class="op">==</span><span class="dv">0</span>) <span class="kw">paste</span>(i, j))</a>
+<a class="sourceLine" id="cb4-2" data-line-number="2"><span class="co">#&gt;  [1] &quot;2 b&quot;  &quot;4 d&quot;  &quot;6 f&quot;  &quot;8 h&quot;  &quot;10 j&quot; &quot;12 l&quot; &quot;14 n&quot; &quot;16 p&quot; &quot;18 r&quot; &quot;20 t&quot;</span></a>
+<a class="sourceLine" id="cb4-3" data-line-number="3"><span class="co">#&gt; [11] &quot;22 v&quot; &quot;24 x&quot; &quot;26 z&quot;</span></a>
+<a class="sourceLine" id="cb4-4" data-line-number="4"></a>
+<a class="sourceLine" id="cb4-5" data-line-number="5"><span class="kw">set.seed</span>(<span class="dv">123</span>)</a>
+<a class="sourceLine" id="cb4-6" data-line-number="6">rand_sequence =<span class="st"> </span><span class="kw">runif</span>(<span class="dv">20</span>)</a>
+<a class="sourceLine" id="cb4-7" data-line-number="7"><span class="co"># gives only locally increasing values</span></a>
+<a class="sourceLine" id="cb4-8" data-line-number="8"><span class="kw">to_vec</span>(<span class="cf">for</span>(<span class="st">`</span><span class="dt">i, j</span><span class="st">`</span> <span class="cf">in</span> <span class="kw">lag_list</span>(rand_sequence)) <span class="cf">if</span>(j<span class="op">&gt;</span>i) j)</a>
+<a class="sourceLine" id="cb4-9" data-line-number="9"><span class="co">#&gt;  [1] 0.7883051 0.8830174 0.9404673 0.5281055 0.8924190 0.9568333 0.6775706</span></a>
+<a class="sourceLine" id="cb4-10" data-line-number="10"><span class="co">#&gt;  [8] 0.8998250 0.3279207 0.9545036</span></a></code></pre></div>
 
 
 

vignettes/Introduction.rmd

@@ -1,5 +1,5 @@
 ---
-title: "List comprehensions in R"
+title: "List Comprehensions in R"
 output: rmarkdown::html_vignette
 vignette: >
   %\VignetteIndexEntry{List comprehensions in R}
@@ -39,3 +39,14 @@ noprimes = to_vec(for (i in 2:7) for (j in seq(i*2, 99, i)) j)
 primes = to_vec(for (x in 2:99) if(!x %in% noprimes) x)
 primes
 ```
+
+You can iterate over multiple lists if you provide several loop variables in backticks:
+```{r}
+to_vec(for(`i, j` in numerate(letters)) if(i %% 2==0) paste(i, j))
+
+set.seed(123)
+rand_sequence = runif(20)
+# gives only locally increasing values
+to_vec(for(`i, j` in lag_list(rand_sequence)) if(j>i) j)
+
+```