Stata count unique values example. Take full advantage of the extra information that panel data provide, while simultaneously handling the peculiarities of panel data. One logic behind that terminology is that if you remove all the duplicates from Title. Learn more about Teams Summary. save `a', replace. Date. First, it gives a compact display of the distinct values of varname. com> Prev by Date: st: Multicollinearity/VIF using -xtlogit,re- models; Next by Date: Re: st: how to program an equivalent of "egen mean" for an equation Hello, I am trying to generate an indicator called mo_all using egen and concat that records all the unique values across a set of variables mo#. Nov 16, 2022 · This first step maps the distinct values of varname to 1, 2, 3, and up to the number of distinct values. . I have different rows of a same type of procedure, same year and same hospital as I am dealing with microdata. There are two methods available for this task. If you don't mind sorting the data, something like this might do what you need. Jul 4, 2023 · We discuss the methods to get unique number of observations in Stata. That is, the field rank is 1 + the number of values that are higher. On the other hand, the DISTINCT keyword is used in the SELECT statement to fetch distinct rows from a table. Code: * Example generated by -dataex-. Efficiently calculate unique values of a variable or group of variables. The problem with using -tab- to count the unique number of values is its row limits: 12,000 rows (Stata/MP and Stata/SE), 3,000 rows (Stata/IC), or 500 rows (Small Stata). duplicates tag generates a variable representing the number of duplicates for each observation. Applying the formula is very easy, and you will be able to master it in no time once you get a hold of it. I used the following two lines of code: egen count_obsv = tag (loc_ID year) This adds a counter to my dataset ( count_obsv) which is 1 (and 0 for every element that has the same combination of loc_ID and year) for every new combination. use the user-written -distinct- command (by the authors of the FAQ you link to); use -findit- or -search- to find and download; see (after installing) Dec 30, 2022 · To count the number of unique values in each column of the data frame, we can use the sapply () function: sapply(df, function(x) n_distinct(x)) team points. Here's a quick example: * Install the unique package ssc inst unique * Load toy dataset sysuse auto, clear * Get a quick report of unique (and total) values for a variable unique mpg * The result will be available as r(unique) return list May 29, 2019 · May 29, 2019. May 30, 2019 · To identify unique values of variables in Stata one option is to use the levelsof command. Apr 10, 2016 · Second column records temperature values with the label "Temperature". Mar 25, 2014 · For example, firsttype has the same value for each occurrence of each distinct username. For instance: id year x1 111 1999 3 111 2000 5 111 2001 6 123 2000 4 123 2001 2 For the above example, there are 2 unique ids (111 and 123). 4 7. egen unique_ttl = tag(ttl_exp) Nov 16, 2022 · Case 4: Dropping duplicates based on all the variables. su group, meanonly Among other things, this second step leaves behind in r(max) the number of distinct values; see [R] summarize for details on saved results. Re: st: number of distinct values for a variable in a group using -collapse-. Caveat: I haven't tested this, and I'm uncertain how well it will work if any of the variables are missing. I cannot really come up with codes that could provide the results I'm looking for. In addition, "Group" needs to be lowercase. Finish by pressing CTRL + SHIFT + ENTER. This option guarantees that the values in the macro that levelsof creates are exactly This Stata FAQ shows how to check if a dataset has duplicate observations. Thus, in the example just given, 1, 2, 3, and 4 would be reported by many as the unique values of the variable in question, even though such distinct values could all be repeated in the data—and, in particular, 2, 3, and 4 are indeed repeated. Oct 28, 2010 · Instead, use -distinct- (Longton and Cox) to display the number of unique values in a variable or a set of variables (see note). bysort record_id: gen aneurysm_id = _n. It has both positive and negative numbers. The duplicates command can list and flag duplicate observations. Using _n and _N in conjunction with the by command can produce some very useful results. Let's suppose that there is a date variable date that is numeric and in good order. Besides the first variable id, which gives an identifier, the other variables (call them A to Z) contain either interesting strings or missing values indicated by ". Below is example of dataset. whatever if group == `i' . At the moment, its main difference from distinct isthat it always considers the variables jointly. id 1 year 2001 - count = 2. I'd like to see all unique characteristics from the particular variable (type: string), excluding all duplicated one. ren firm competitor. gen long original_order = _n. This will also show value labels that may not have corresponding values in the data. To count the unique values (don't be overwhelmed), we add the SUM function, 1/, and replace 5 with A1:A6. stata. id 2 year 2000 - count = 1. There are different methods of doing this i. From: Michael Barker <mdb96statalist@gmail. idom v4741. 2 z. In order to get the unique values of a variable (for example how many times an identifier occurs among observations) there are a few different approaches we can try. Hopefully that helps. Each observation in my data represents a respondent. Jan 17, 2023 · library (dplyr) #count unique values in each column sapply(df, function (x) n_distinct(x)) team points 4 7 From the output we can see: There are 7 unique values in the points column. clear input year str2 state str11 document 2009 AS 09420849920 2006 AS 91444492147 2008 AS 91444492147 2007 AK 47080474742 2006 AK 90190072284 2007 AK 90190072284 2006 AK 10744281448 2009 AL 22408712220 2006 AS 92974278888 2008 AL 27189228210 2009 AS We use the COUNTIF function. As far as Stata is concerned, any change to the variables on which the data are sorted means that the data are no longer sorted, even if the change actually leaves the order unchanged. A convenient alternative is provided by the "unique" package. drop if dup>0. Counting distinct values: there was a survey of the terrain by Gary Longton and myself in SJ-8-4 dm0042 . For example, to count the number of 5's, use the following function. Counting distinct strings across a set of variables. So in the above example the new column would output: over_three_less_than_six 0 1 4 1. Code: by a b c, sort: generate count = _N egen tolist = tag (a b c), missing list a b c count if tolist drop count tolist. drop if dup>1. I want it to ignore missing values. Obs. values) specifies the variable whose unique values denote a subobservation. list. tabulate won't play with very large numbers of rows, one of various reasons for distinct (SJ). codebook, contract, unique, distinct, le May 20, 2021 · The UNIQUE keyword in SQL plays the role of a database constraint; it ensures there are no duplicate values stored in a particular column or a set of columns. Jan 28, 2013 · What is the easiest way to create a new variable, 'over_three_less_than_six' to count how many people per location gave 3 or more gifts but less than 6. desc foreign. } Jan 15, 2019 · I would like to generate a variable "total" that will count the number of times "NP" shows up in each row. facility_id A would get count equal to 3 count counts the number of observations that satisfy the specified conditions. I want to generate a variable that is the count of unique dates for each row. For instance, for entity 1, year 2010 I would have 2 (The aim is to avoid double counting!). You can go. One clue to by: being useful here is the structure of a grouping of the variable x into several distinct values. In this simulation I have manually counted, in the var -total-, the number I'm seeking advice on how to write code for counting. com count may strike you as an almost useless command, but it can be one of Stata’s handiest. but the results will be arbitrary unless there is some other information, say a date variable, to provide a rationale for the ordering. If a combination of values is unique (occurs once only) then _N is 1 and the returned value is 0. foreach i of num 1/`r(max)' {. If no conditions are specified, count displays the number of observations in the data. g. Jan 24, 2019 · Teams. Jul 23, 2019 · Below code, a combination of Mike's & Nick's (as mentioned by Reeves in #6) might be a solution, which, while adding the wanted counting, also tries to keep the original data structure. -distinct- has other options and may be used with the Nov 16, 2022 · The problem of counting distinct values within variables has often been addressed; see, in particular, the FAQ: How do I compute the number of distinct observations? This FAQ suggests that we can attack this problem through the sequence reshape calculate number of distinct observations reshape. This will be 0 for all unique observations. 1. I do not need unique values in each row, i only need the count of specific values by row. duplicates examples lists one example for each group of duplicated observations. The list subcommand lists the duplicate observations: . 19 Apr 2016, 22:24. Picking up where case 3 left off, this is no different from case 2. Stata. Oct 10, 2017 · What I want is simply to summarize my dataset by unique categories such as Economics (3), Psychology (2), Biology (1) (so the sum of all can be superior to the number of observations). The best place to learn about SQL and databases is LearnSQL. For this to work, you would have to install -egenmore- (SSC) first. The command is very straight forward. Thus, I would like to create a variable "a" which refers to variable"x" in the following pattern: Feb 19, 2022 · Thanks for the data example and clear description. Jan 19, 2019 · Two additional options: 1) You can list the value labels attached to each value. and so on, with x, y, z indicating how many observations ==2 there are per row in the dataset. I have a dataset in Stata and want to count by group ( loc_ID) and year. com count may strike you as an almost useless command, but it can be one of Stata’s Nov 16, 2022 · The solution. Fit linear models or nonlinear models for binary, count In the simplest case, the code would be bysort year CLMS: gen uniqclms = _n == 1 by year: replace uniqclms = sum (uniqclms) by year: replace uniqclms = uniqclms [_N] So we tag every distinct value by 1, just once, the first time it occurs. Counting with by. So, you should be doing something like the following: Code: egen fysperklinik=group(BKlinik_ID fysb_userId) bysort BKlinik_ID: tab fysperklinik. string specifies that j() may contain string values. edu. sort group score. Study the time-invariant features within each panel, the relationships across panels, and how outcomes of interest change over time. duplicates list x1 x2 x3. 3. Jul 28, 2020 · 1 Answer. All we need to do is tag the first occurrence of each distinct value, and then count those first occurrences in sequence. Code: clear. Author. This is easy in R, but I'd like to stay with Stata for this project. A key to that is the egen function tag() just used, for example Sep 10, 2021 · I have unique IDs in rows where columns are the IDs of their 'sent' friends. The track option calculates the track rank of exp: the lowest value is ranked 1, and there is no correction for ties. To install: ssc install dataex. Share. First we -rename- variables, so that they have a common prefix, say foreach v of var A-Z { rename `v' S_`v' } Then we -reshape- to long: reshape long S_ , i (id) string Now our count of distinct strings could be bysort id S_ : gen nvals = _n == 1 by id : replace nvals = sum (nvals) by id : replace nvals = nvals [_N] Not so fast, however! If Mar 10, 2017 · the issue is that you are trying to perform two commands on the same line: egen and tab. When posting example data, if your real data contains missing values of variables, your example data should, too. Often the easiest way to get at the number of distinct values present is to fire up tabulate and retrieve the number of rows as r(r). 2levelsof— Distinct levels of a variable hexadecimal specifies that hexadecimal format %21x be used when varname is numeric. From: "Jia Peng" <jiapengcass@gmail. com> References: st: How to count occurrences of specific value. Fri, 24 Feb 2012 23:57:59 +0000. harvard. Please do read and act on FAQ Advice #12. 400713 6. input group id visitno str25 allcolors total. values lists the unique values to be used from varname, which typically are not explicitly stated because reshape will determine them automatically from the data. com tabulate with the summarize() option produces one- and two-way tables of summary statistics. gunique is a faster alternative to unique. Of course, to use the by command we must first sort our data on the by variable. It reports the number of uniquevalues for the varlist. Hi, I have a cross-section panel data that is unbalanced. In practice, when people want to do this, the 5 largest or smallest values commonly are distinct and come from a straggly tail of a skewed distribution. I tried code: egen count = nvals (session_district), by (facility_id) would give me count for distinct observations by session_district, i. You say place and Place in different places, but you don't give us a data example to make clear what is going on. Code: tempfile a. To count unique values in our data set, we use a combination of the IF, SUM and COUNTIF functions. Aug 16, 2015 · Hi, I would like to count the frequency of an observation within a variable. joinby JobCategory city using `a'. Jun 3, 2020 · I am using Stata version 15 to calculate the number of distinct cases (firm) by a group of two variables (entity and year). Then we sum all the 1s, and so on. 2. com. 0 x. Code: sysuse auto. isid x1 x2 x3. otherwise known as the Stata two-step. egen unique_ttl = tag(ttl_exp) count if catvar==3 Count observations for each value of catvar by catvar: count Menu Data > Data utilities > Count observations satisfying condition Syntax count if in by and collect are allowed; see [U] 11. Thus, in row 1 "total" would be equal to "5" as there are 5 "NP"s. Count by groups and collapse. Then we use . id. There are 7 unique values in the points column. Changing mpg from 12 to 10, however, does not really affect the sort order. See [D] format. This user-written command is nice because it creates a variable that captures all the information needed to May 29, 2019 · May 29, 2019. In the example shown, the formula in F5 is: = COUNTA ( UNIQUE (B5:B16)) which returns 7, since there are seven unique colors in B5:B16. as longs take up 4 bytes not 8 and can take values of more than 2 Jun 30, 2022 · For ideas on how to handle distinct values, often called unique values, you could start with Cox and Longton (2008). I would like to count with id and then year. Apr 20, 2016 · How to count with two conditions. For example: will display the total number of non-missing observations and the total number of unique values for rep78. 1 y. . More commonly, it is useful when you desire to cycle through the distinct values of varname with (say) foreach; see Re: st: How to count occurrences of specific value. Let’s load up the nlsw88 dataset and look at the variable representing total work experience ( ttl_exp ): sysuse nlsw88, clear. 10 Prefix commands. Stata To. One trick to do this is to reshape wide and back to long, then replace missings with 0. Sorted by: 0. id 2 year 2001 - count = 1. Say the maximum is 42. ". To count unique values in a set of data, you can use the UNIQUE function together with the COUNTA function. For example if want to count observations with positive temperature I use this command "count if Temperature>0". You can do the above by using by: , which is one of the most versatile features of Stata. I want to use "count if" function for counting positive and negative temperature values. ----------------. I want to recreate the variable v4741 counting how many times this specific ID appears. The first example will use commands available in base Stata. Nov 20, 2017 · while true that -unique- (SSC) is not unique - it is also not the same as -distinct- when more than one variable is included in the command; here is an example: Code: May 29, 2016 · I am hoping to generate a variable (nsites2) that when tabulated will give a frequency distribution of the number of observations that ==2 per row e. The general form of the formula to count unique values looks like this: =SUM (IF (COUNTIF (range, range)=1,1,0)) Oct 2, 2015 · You got what you asked for. by group: generate n1 = _n. Example 1 May 28, 2016 · * there are unlabelled values in the data * values in the data have no associated labels. Note: The formula bar indicates that this is an array formula by enclosing it in curly braces {}. It also has slighly differentoptions. However, that code would need to be modified if you had missing values Jul 5, 2023 · You can check for duplicate observations in Stata in the following ways: The isid command can detect duplicate observations: . When combined with the by prefix, it can produce n-way tables as well. Mar 13, 2016 · I have a dataset with procedures performed by type (type), per hospital code (cnes) and year (year). set obs 8. tab nsites2 // would hopefully give: ==2 Freq. Our change in example 2 did change the order of the data, so Stata was correct. Q&A for work. Aug 31, 2013 · In addition, egen is only to be used for convenience, never speed. That is, the track rank is 1 + the number of values that are lower. Jul 1, 2014 · PS: I know this has nothing to do with Stata (but it may inspire someone) with an actually programming language I would try something such as: Having a cycle doing citing column and checking if equal to the one before Having an auxiliary empty vector Having a second cycle within the first that wouldsee if the current cat was in the vector and Count UNIQUE values in Excel. Remarks are presented under the following headings: One-way tables Two-way tables One-way tables Example 1 We have data on 74 automobiles. Feb 14, 2019 · How to list all unique values in the variable? 14 Feb 2019, 13:39. From the Stata documentation: levelsof serves two different functions. If you want to drop all duplicate observations, including the first occurrence, type. Hello, I see 'unique' or 'distinct' commands will show the total number of unique values in the variable, but they don't actually list each of the unique values. Jun 19, 2015 · 18 Jun 2015, 15:33. Nicholas J. Specifically, my code is egen mo_all = concat(mo1_1 mo2_1 mo3_1 mo4_1 mo5_1 mo6_1 mo7_1 mo8_1 mo9_1 mo10_1 mo11_1 mo12_1 mo13_1 mo14_1 mo15_1 mo16_1), punct(" ") Mar 29, 2020 · Lesson to those reading along: in many, perhaps most, data management problems, the presence of missing values in a variable requires some kind of explicit attention in the code. Since my dataset has over 6000 observations, what commands should I use to generate a Nov 16, 2022 · Panel/longitudinal data. Remarks and examples stata. Often you will want to use each value just once. The second example will use a user-written program. The unique option calculates the unique rank of exp: values are ranked 1, :::, #, and Creating a variable equal to the count of unique values across varlist for each observation I have data with a bunch of different date fields that may or may not contain the same information. statalist@hsphsun2. 7593667. Apr 22, 2021 · Dear Stata community, I'd like to generate a variable that records the number of unique values of a variable (var1) within each value of another variable (var2) over a rolling time window defined by a date variable. I would like to get the result. There is a detailed review of this question in. Identify the value label if you don't know it with the describe command followed by the lab list command. 1 like. To get a count of 'received' friends, I need to get a count for how many times an ID appears across all columns and rows of the dataset. e. by group: generate n2 = _N. Re: st: counting unique ids. duplicates list lists all duplicated observations. Otherwise _N is 2 or more for each group and duplicated (identical) observations are assigned values 1, 2 (and so forth, as appropriate). Dec 27, 2016 · however that deals with one-word stringvars, whereas I wish to count the number of unique and distinct words with a stringvar that has multiple words. On two separate lines. Subject. For example, the complete offending code with a minimal data input that recreates the problem. stata Share Jan 19, 2018 · count() will accept string variables. Cox, Durham University, UK. In the expample above, display r (r) returns the number of rows in the table, that is, the number of unique observations for variable varname. Aug 19, 2020 · Here is a sample of what I have: - idom is the ID that I created for each member of an specific household and v4741 is the variable with how many members this household has. There are 4 unique values in the team columm. The problem. If you want to drop all duplicate observations but keep the first occurrence, type. 1. replace _count = _count + (move`j' == playerlist) replace _count = _count + (move`j' == playerlist) Even if you had been determined to use egen, the loop need only be over the distinct values of playerlist, not all the observations. Each example represents the first occurrence of each group in the dataset. id 1 year 2000 - count = 1. Connect and share knowledge within a single location that is structured and easy to search. May 14, 2019 · Hence, as illustrated in the example, although facility_id will occur distinctly 3 times, because there are only two unique session_district, the count would be 2. We will stop a long way short of the statistics of extremes. rz bx ku gs wo rq xf fw wp qh