python - Calculate STD manually using Groupby Pandas DataFrame -

-

I was trying to write a solution, which is a different and a manual for calculating a mean and STD The way.

I have created 

  a = ["Apple", "Banana", "Cherry", "Apple"] B = [3,4,7,3] C = [5,4,1,4] D = [7,8,3,7] Pd DF = PD to import pandals DataFrame (index = class (4), column = list ("ABCD")) DF ["A"] = A DF ["B"] = BDF ["C"] = C DF ["D"] = D

Again, I made a list of A duplication. Then I went through the group all the time of the objects and calculated the solution. 

  import as np l = list (set (df.A)) df.groupby ('A', As_index = False) listMean = [0] * len (df.C) ListSTD = [0] * L in the LAN (df.C) X: s = np.mean (df [df ['A'] == x] for C =.) = Z = [index for index, enumerate In the object (df ['a']. Value] x == item i for z: listMean [i] = s in: s = np.std (df [df ['a'] == X] .cvalues) z = index for index, enumerate item (df ['a']. Value) if x == item] i in Z: listSTD [i] = s df ['c'] = ListMean df ['E'] = listSTD print df

I used description () grouping To calculate the mean, STD, "A" by 

  print df.groupby ('A'). Description ()

and test the suggestion solution: 

  result = df.groupby (['a'], as_index = False) .gg ({ 'C': ['mean', 'std'], 'b': 'first', 'd': 'first'})

I have noticed that when I get the STD ("E"), I get different results. I'm just curious, what did I miss?

contains: population SD and sample SD

population SD

Enter image details here

sample sd

Enter image details here

It is used when the value is There is only one sample from the universe.

np.std by default population counts SD, while panda ' series.std calculates sample SD by default. [42]: np.std ([4,5]) outside [42]: in 0.5 [43]: np.std ([4,5], ddof = 0) 

  Outside [43]: 0.5 in [44]: np.std ([4,5]], Ddof = 1 out [44]: 0.70710678118654757 in [45]: x = pd.Series ([4,5]) [46]: x.std () out [46]: 0.70710678118654757 [47]: X.std (ddof = 0) out [47]: 0.5

ddof < / Code> for cents and "degrees of freedom", and control the number that occurred in the SD formula from N .

The formula images appear above. There is the "uncorrected sample standard deviation" I called the population SD, and the "true sample standard deviation" sample is SD.


Comments

Post a Comment

Popular posts from this blog

java - Can't add JTree to JPanel of a JInternalFrame -

-
Image
There are two panels in my JInternalframe. I want to add TopPanel to Jtree to nominate another. But I can not add Jaitari to the top of the panel. Please help me in this piece of code: DefaultMutableTreeNode root = new DefaultMutableTreeNode ("deck"); DefaultMutableTreeNode Item Clubs = New DefaultMutableTreeNode ("Club"); AddAllCard (itemClubs); Root.add (itemClubs); DefaultMutableTreeNode item = New DefaultMutableTreeNode ("Diamonds"); AddAllCard (itemDiamonds); Root.add (itemDiamonds); DefaultMutableTreeNode Itemspads = New DefaultMutableTreeNode ("Spades"); AddAllCard (itemSpades); Root.add (itemSpades); DefaultMutableTreeNode item increases = new DefaultMutableTreeNode ("heart"); AddAllCard (itemHearts); Root.add (itemHearts); Default Trimodel Tree Model = New DefaultTreeModel (Route); Tree = new jetty (tree modal); ScrollPane = new JScrollPane (tree); // scrollPane.setViewportView (tree); . ScrollPane.getViewport () add (tr
Read more

javascript - data.match(var) not working it seems -

-
OK, I have this small block code, which is to scanned a number on the website, but for some reason There is a hip that it is not scanning at all. var regenges = / \ & lt; Span class = "currency-robux" data-to-"item-private-value-price" & gt; ([\ D,]) \ & LT; \ / Span \ & gt; /; Var ValueCiling = Data. Match (reggae); Value-song = number (value slicing location (",", "")); Is there anything wrong with that? This is related to the if statement if (value sling and lieutenant; = price watching) { < P> A function calls to move from there, but for some reason it does not seem to run at all. So I think the Regex is wrong but I'm not sure how. (There is a variable in PriceWinking , this is a snippet from the code.) On the website, I'm trying to remove it. & lt; Span class = "robux" data-plus = "item-privatesale-price" & gt; 115 & lt; / Span & gt; Keep in mind
Read more

javascript - How can I pause a jQuery .each() loop, while waiting for user input? -

-
Before I continue to get a jQuery .each loop to wait for user input There is a problem in repeatedly repeating This is my code (I have commented on what I would like to do): & lt; Html xmlns = "http://www.w3.org/1999/xhtml" & gt; & Lt; Top & gt; & Lt; Link rel = "stylesheet" type = "text / css" href = "common_components.css" /> & Lt; Meta http-equiv = "content-type" content = "text / html; charset = UTF-8" /> & Lt; Link rel = "stylesheet" href = "slider.css" & gt; & Lt ;? Php include_once 'common_components.php'; $ Query = $ dbh- & gt; Queries ("SELECT movies_dir FROM settings"); $ Line = $ query- & gt; Obtain (PDO :: FETCH_ASSOC); Date_default_timezone_set ('UTC'); Echo "& lt; title & gt; movie scanner & lt; / title & gt;"; ? & Gt; & Lt; Script src = "jquery.min.js" & gt; &am
Read more