diff options
Diffstat (limited to 'manual/v1.3/index.html')
| -rw-r--r-- | manual/v1.3/index.html | 44 |
1 files changed, 22 insertions, 22 deletions
diff --git a/manual/v1.3/index.html b/manual/v1.3/index.html index c85b5f51..921eb42a 100644 --- a/manual/v1.3/index.html +++ b/manual/v1.3/index.html @@ -130,8 +130,8 @@ simpler:</p> <p>jq filters run on a stream of JSON data. The input to jq is parsed as a sequence of whitespace-separated JSON values which are passed through the provided filter one at a time. The -output(s) of the filter are written to standard out, again as a -sequence of whitespace-separated JSON data.</p> +output(s) of the filter are written to standard output, as a +sequence of newline-separated JSON data.</p> <p>You can affect how jq reads and writes its input and output using some command-line options:</p> <ul> @@ -291,9 +291,8 @@ the value at the key "foo", or null if there's none present.</p> </h3> <p>You can also look up fields of an object using syntax like <code>.["foo"]</code> (<code>.foo</code> above is a shorthand version of this). This -one works for arrays as well, if the key is an -integer. Arrays are zero-based (like javascript), so <code>.[2]</code> -returns the third element of the array.</p> +one works for arrays as well, if the key is an integer. Arrays +are zero-based, so <code>.[2]</code> returns the third element of the array.</p> <p>The <code>.[10:15]</code> syntax can be used to return a subarray of an array. The array returned by <code>.[10:15]</code> will be of length 5, containing the elements from index 10 (inclusive) to index @@ -619,7 +618,7 @@ element of the input array.</p> strings, booleans, arrays, objects (which in JSON-speak are hashes with only string keys), and "null".</p> <p>Booleans, null, strings and numbers are written the same way as -in javascript. Just like everything else in jq, these simple +in JSON. Just like everything else in jq, these simple values take an input and produce an output - <code>42</code> is a valid jq expression that takes an input, ignores it, and returns 42 instead.</p> @@ -2240,7 +2239,7 @@ as <code>C</code> otherwise.</p> means that you'll sometimes have to be more explicit about the condition you want: you can't test whether, e.g. a string is empty using <code>if .name then A else B end</code>, you'll -need something more like <code>if (.name | count) > 0 then A else +need something more like <code>if (.name | length) > 0 then A else B end</code> instead.</p> <p>If the condition <code>A</code> produces multiple results, then <code>B</code> is evaluated once for each result that is not false or null, and <code>C</code> is evaluated @@ -2533,7 +2532,7 @@ array, perhaps one for each element or for a loop counter. In jq, it's simply <code>add / length</code> - the <code>add</code> expression is given the array and produces its sum, and the <code>length</code> expression is given the array and produces its length.</p> -<p>So, there's generally a cleaner way to solve most problems in jq that +<p>So, there's generally a cleaner way to solve most problems in jq than defining variables. Still, sometimes they do make things easier, so jq lets you define variables using <code>expression as $variable</code>. All variable names start with <code>$</code>. Here's a slightly uglier version of the @@ -2667,23 +2666,24 @@ input's <code>.foo</code> field to each element of the array.</p> </section> - <section id="Reduce"> + <section id="reduce"> <h3> - Reduce + <code>reduce</code> </h3> - <p>The <code>reduce</code> syntax in jq allows you to combine all of the -results of an expression by accumulating them into a single -answer. As an example, we'll pass <code>[3,2,1]</code> to this expression:</p> + <p>The <code>reduce</code> syntax allows you to combine all of the results of +an expression by accumulating them into a single answer. +The form is <code>reduce EXP as $var (INIT; UPDATE)</code>. +As an example, we'll pass <code>[1,2,3]</code> to this expression:</p> <pre><code>reduce .[] as $item (0; . + $item) </code></pre> <p>For each result that <code>.[]</code> produces, <code>. + $item</code> is run to -accumulate a running total, starting from 0. In this -example, <code>.[]</code> produces the results 3, 2, and 1, so the -effect is similar to running something like this:</p> -<pre><code>0 | (3 as $item | . + $item) | - (2 as $item | . + $item) | - (1 as $item | . + $item) +accumulate a running total, starting from 0 as the input value. +In this example, <code>.[]</code> produces the results <code>1</code>, <code>2</code>, and <code>3</code>, +so the effect is similar to running something like this:</p> +<pre><code>0 | 1 as $item | . + $item | + 2 as $item | . + $item | + 3 as $item | . + $item </code></pre> @@ -2697,14 +2697,14 @@ effect is similar to running something like this:</p> <table> <tr><th></th><td class="jqprogram">jq 'reduce .[] as $item (0; . + $item)'</td></tr> - <tr><th>Input</th><td>[10,2,5,3]</td></tr> + <tr><th>Input</th><td>[1,2,3,4,5]</td></tr> <tr> <th>Output</th> - <td>20</td> + <td>15</td> </tr> </table> @@ -2973,7 +2973,7 @@ that we did before:</p> "Defining Functions" : "DefiningFunctions", - "Reduce" : "Reduce", + "reduce" : "reduce", "Advanced features" : "Advancedfeatures" , |