{"id":77811,"date":"2016-04-14T00:01:51","date_gmt":"2016-04-14T07:01:51","guid":{"rendered":"https:\/\/blogs.technet.microsoft.com\/heyscriptingguy\/?p=77811"},"modified":"2019-02-18T09:10:49","modified_gmt":"2019-02-18T16:10:49","slug":"calculate-percentage-character-frequencies-from-a-text-file-by-using-powershell","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/scripting\/calculate-percentage-character-frequencies-from-a-text-file-by-using-powershell\/","title":{"rendered":"Calculate percentage character frequencies from a text file by using PowerShell"},"content":{"rendered":"

Summary<\/strong>: Learn how to use Windows PowerShell to calculate the percentage of how often a character appears in a text file.<\/p>\n

This is the fifth post in a multi-part series of blog posts that deal with how to determine letter frequency in text files. To fully understand this post, you should read the entire series in order.<\/p>\n

Here are the posts in the series:<\/p>\n

    \n
  1. Letter frequency analysis of text by using PowerShell<\/a><\/li>\n
  2. How to skip the beginning and ending of a file with PowerShell<\/a><\/li>\n
  3. Read a text file and do frequency analysis by using PowerShell<\/a><\/li>\n
  4. Compare the letter frequency of two text files by using PowerShell<\/a><\/li>\n
  5. Calculate percentage character frequencies from a text file by using PowerShell<\/li>\n
  6. Additional resources for text analysis by using PowerShell<\/a><\/li>\n<\/ol>\n

    Okay, I will admit that I am just playing around, but I wanted to calculate the percentages of letter frequencies in a text file. For this example, I am using A Tale of Two Cities <\/em>as a text file. You should refer to earlier blog articles about this topic so that what I write will have a chance of making sense.<\/p>\n

    Create a header for my report<\/h2>\n

    The first thing I want to do is create a header for my report that I will display. To do this, I create an expanding here<\/strong> string. The basic here<\/strong> string is a bit fussy, but it begins with @\u201d<\/span> that is immediately followed by a return. Then it ends a new line that has \u201c@<\/span>.<\/p>\n

    Here’s the here<\/strong> string I use. The thing that is pretty cool is that it is the first thing I am defining in my script, and so neither the value of the $path<\/code> nor the total number of characters are yet determined. These will be evaluated when it is time to display the header. Until then, here\u2019s the here<\/strong> string:<\/p>\n

    $header = @”<\/span>\n ****************************************************************<\/span>\n |<\/span>\n | Letter Frequency Analysis<\/span>\n | of $path<\/span>\n | Analyzing $($total) characters …<\/span>\n |<\/span>\n ****************************************************************<\/span>\n “@<\/span><\/p>\n

    Read the contents of the file and count the characters<\/h2>\n

    The next thing I need to do is to read the contents of the text file and count the characters in the file. I assign the path of\u00a0my file to a variable that I name $path<\/span>. I then use Get-Content<\/strong> to read the contents of the file, and I store the results in the $a<\/span> variable. I now want to count how many characters are in the file. Because I have the entire contents of the text file in the $a<\/span> variable, I can use that. Although, the count<\/span> property contains the number of lines in the file, it does not contain the number of characters. The easy way to obtain this information is to use the Measure-Object<\/strong> cmdlet and call the -Character<\/strong> switch to cause it to count characters. I then directly access the Characters<\/strong> property from the object returned from the Measure-Object<\/strong> cmdlet and store the number of characters in the $total<\/span> variable. I then display the header here<\/strong> string that I previously stored in the $header<\/span> variable. This code is shown here:<\/p>\n

    $path = ‘C:\\fso\\ATaleOfTwoCities.txt’<\/span>\n $a = Get-Content $path<\/span>\n $total = ($a | measure -Character).characters<\/span>\n $header<\/span><\/p>\n

    The code that I use to count the frequency of the characters was explained in an earlier article, so the code is shown here without additional comment:<\/p>\n

    $ajoined = $a -join “`r”<\/span>\n $ajoinedUC = $ajoined.ToUpper()<\/span>\n $ajoinedUC.GetEnumerator() |<\/span>\n group -NoElement | sort count -Descending<\/span><\/p>\n

    Use custom properties in Select-Object to get percentages<\/h2>\n

    So, now I use the Select-Object<\/strong> cmdlet, and I compute some custom properties to display. This is a great technique that works well with the pipeline. It takes the form of the following:<\/p>\n

    @{ LABEL = STRING ; EXPRESSION = SCRIPTBLOCK}<\/code><\/p>\n

    The first custom property simply displays the Name<\/strong> of the character. I add a column heading called \u201cCharacter\u201d, and under that column heading, I will display each character.<\/p>\n

    For the second property, I use the Count<\/strong> property that comes from my Group-Object<\/strong> cmdlet that groups all of the characters together. My Sort-Object<\/strong> command sorts these from largest number to smallest number. I place the Count<\/strong> property below a column heading that I call \u201cFrequency\u201d.<\/p>\n

    The last property is the most complex. I add a column heading called \u201cPercent\u201d. I calculate the percentage of representation by dividing the letter frequency by the total number of characters. I then use the built-in Percentage<\/strong> format specifier,\u00a0p<\/strong>, in conjunction with the -f<\/strong> format operator. I tell it to calculate percentage from my number and to display it to two decimal places of accuracy. The total Select<\/strong> statement is shown here:<\/p>\n

    Select @{L = ‘Character’; E = {$_.Name} },<\/span>\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 @{L = ‘Frequency’ ; E = {$_.count} },<\/span>\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 @{L = ‘Percent’ ; E = {“{0:p2}” -f ($_.count \/ $total)}}<\/span><\/p>\n

    The complete script<\/h2>\n

    The complete code is shown here:<\/p>\n

    $header = @”\n****************************************************************\n|\n| Letter Frequency Analysis\n| of $path\n| Analyzing $($total) characters …\n|\n****************************************************************\n“@\n$path = ‘C:\\fso\\ATaleOfTwoCities.txt’\n$a = Get-Content $path\n$total = ($a | measure -Character).characters\n$header\n$ajoined = $a -join “`r”\n$ajoinedUC = $ajoined.ToUpper()\n$ajoinedUC.GetEnumerator() |\ngroup -NoElement | sort count -Descending |\nSelect @{L = ‘Character’; E = {$_.Name} },<\/span>\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 @{L = ‘Frequency’ ; E = {$_.count} },<\/span>\n\u00a0 \u00a0 \u00a0 \u00a0 \u00a0 \u00a0 @{L = ‘Percent’ ; E = {“{0:p2}” -f ($_.count \/ $total)}}<\/span><\/p>\n

    The script is in the figure here:<\/p>\n

    \"Screenshot<\/a><\/p>\n

    When I run the script, the following output is shown:<\/p>\n

    \"Screenshot<\/a><\/p>\n

    I invite you to follow me on Twitter<\/a> and Facebook<\/a>. If you have any questions, send email to me at scripter@microsoft.com<\/a>, or post your questions on the Official Scripting Guys Forum<\/a>. Also check out my Microsoft Operations Management Suite Blog<\/a>. See you tomorrow. Until then, peace.<\/p>\n

    Ed Wilson<\/strong>\nMicrosoft Scripting Guy<\/p>\n","protected":false},"excerpt":{"rendered":"

    Summary: Learn how to use Windows PowerShell to calculate the percentage of how often a character appears in a text file. This is the fifth post in a multi-part series of blog posts that deal with how to determine letter frequency in text files. To fully understand this post, you should read the entire series […]<\/p>\n","protected":false},"author":596,"featured_media":87096,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[568,684,678,641],"tags":[416,164,3,617,45],"class_list":["post-77811","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-hey-scripting-guy","category-math","category-text","category-windows-powershell","tag-formatting-output","tag-math","tag-scripting-guy","tag-text","tag-windows-powershell"],"acf":[],"blog_post_summary":"

    Summary: Learn how to use Windows PowerShell to calculate the percentage of how often a character appears in a text file. This is the fifth post in a multi-part series of blog posts that deal with how to determine letter frequency in text files. To fully understand this post, you should read the entire series […]<\/p>\n","_links":{"self":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/77811","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/users\/596"}],"replies":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/comments?post=77811"}],"version-history":[{"count":0,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/posts\/77811\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media\/87096"}],"wp:attachment":[{"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/media?parent=77811"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/categories?post=77811"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/devblogs.microsoft.com\/scripting\/wp-json\/wp\/v2\/tags?post=77811"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}