How does 'pg_tablespace_size' works? - postgresql-11

I ran following command and got followings, but a bit confuesed about table size manipulation becaue I do not know how does pg_tablespace_size work:
my_db=> select pg_size_pretty(pg_total_relation_size('my_table'));
pg_size_pretty
----------------
123 GB
(1 row)
my_db=> select pg_size_pretty(pg_indexes_size('my_table'));
pg_size_pretty
----------------
34 GB
(1 row)
my_db=> select pg_size_pretty(pg_relation_size('my_table'));
pg_size_pretty
----------------
27 GB
(1 row)
rest_space = pg_total_relation_size('my_table') - (pg_indexes_size('my_table') + pg_relation_size('my_table'))
But I do not know where is rest_space (62 GB), I would be grateful if someone explain this.

pg_relation_size(<tablename>) is actually shorthand for pg_relation_size(<tablename>,’main’) (see the documentation). There are also the free space map (fsm), visibility map (vm), and init forks that factor into the full size.
I think you would get the correct results if you did pg_total_relation_size() = pg_table_size() + pg_indexes_size()

Related

combining multiple items to create one dummy variable

I have 7 items/variables in Stata that address the same survey question. These 7 items are each different weight control behaviors (diet, exercise, pills, etc.). I am trying to combine these variables to create a single weight control behavior dummy variable that is coded as yes (did engage in weight control) and no (did not engage in weight control).
The response options for each variable look something like this for a given weight control behavior
dieted
11438 0 not marked
2771 1 marked
16 6 refused
6508 7 legitimate skip
13 8 don’t know
Here is my code. I re-coded 6,7,8 for all 7 vars as missing:
tab1 h1gh30a-h1gh30g,m`
foreach X of varlist h1gh30a-h1gh30g {
replace `X'=. if `X' > 1
}
egen wgt_control= rowmax(h1gh30a-h1gh30g)
ta wgt_control
gen wgt_control_new=wgt_control
replace wgt_control_new = 1 if wgt_control>0 & wgt_control!=.
replace wgt_control_new= 0 if wgt_control <1
ta wgt_control_new
I used rowmax() to combine all 7 items but my issue is that the response option 0 or No doesn't appear when I tabulate it. I only get those who responded yes=1.
Here is a suggestion with a reproducible example for what I think is the cleanest approach. I also included some unsolicited advice about survey data best practices
* Example generated by -dataex-. For more info, type help dataex
clear
input double(h1gh30a h1gh30b h1gh30c)
1 1 1
1 0 1
6 1 8
0 0 0
7 6 8
end
* Explicit coding is better, so if possible, which it is with 7 vars,
* create a local with the vars are explicitly listed
local wgt_controls h1gh30a h1gh30b h1gh30c
* Recode is a better command to use here. And do not destroy information,
* there is a survey data quality assurance difference between respondent
* refusing to answer, not knowing or question skipped. You can replace this
* survey codes with these extended missing values that behaves like missing values
* but retain the differences in the survey codes
recode `wgt_controls' (6=.a) (7=.b) (8=.c)
* While rowmax() could be used, I think it seems like anymatch() fits
* what you are trying to do better
egen wgt_control = anymatch(`wgt_controls'), values(1)
There is no minimal reproducible example here, so we can't reproduce the problem independently.
From your code, it seems that h1gh30a-h1gh30g are recoded so that all are 0, 1 or missing, so their maximum takes one of the same values.
gen wgt_control_new = wgt_control
replace wgt_control_new = 1 if wgt_control>0 & wgt_control!=.
replace wgt_control_new= 0 if wgt_control <1
seems to boil down to cloning the variable:
gen wgt_control_new = wgt_control
In short, I can't see a reason in your code why you should never see 0 as a possible result.
EDIT
A minimal check on whether there are zeros that aren't showing up as they should might be
egen max = rowmax(h1gh30a-h1gh30g)
list high30a-high30g if max == 0
```

How can we use clustering results in weka ?

I am using Weka for my internship but I have a little knowledge about data mining. So, maybe someone knows how can I apply the following results on my data-sets to get all data by cluster ? The method that I use now is to compute distances between my attributes and the mean value of each cluster then I classify them by the nearest value. But this method is too rough for me .
=== Run information ===
Scheme:weka.clusterers.EM -I 100 -N -1 -M 1.0E-6 -S 100
Relation: wcet_cluster6 - Copie-weka.filters.unsupervised.attribute.Remove-R1-3,5-weka.filters.unsupervised.attribute.Remove-R5-12
Instances: 467
Attributes: 4
max
alt
stmt
bb
Test mode:evaluate on training data
=== Model and evaluation on training set ===
EM
Number of clusters selected by cross validation: 6
Cluster
Attribute 0 1 2 3 4 5
(0.28) (0.11) (0.25) (0.16) (0.04) (0.17)
==================================================================
max
mean 9.0148 10.9112 11.2826 10.4329 11.2039 10.0546
std. dev. 1.8418 2.7775 3.0263 2.5743 2.2014 2.4614
alt
mean 0.0003 19.6467 0.4867 2.4565 44.191 8.0635
std. dev. 0.0175 5.7685 0.5034 1.3647 10.4761 3.3021
stmt
mean 0.7295 77.0348 3.2439 12.3971 140.9367 33.9686
std. dev. 1.0174 21.5897 2.3642 5.1584 34.8366 11.5868
bb
mean 0.4362 53.9947 1.4895 7.2547 114.7113 22.2687
std. dev. 0.5153 13.1614 0.9276 3.5122 28.0919 7.6968
Time taken to build model (full training data) : 4.24 seconds
=== Model and evaluation on training set ===
Clustered Instances
0 163 ( 35%)
1 50 ( 11%)
2 85 ( 18%)
3 73 ( 16%)
4 18 ( 4%)
5 78 ( 17%)
Log likelihood: -9.09081
Thanks for your help!!
I think no-one can really answer this. Some tips off the top of my head.
You have used the EM clustering algorithm, see animated gif on wikipedia page. From Weka's Documentation Synopsis:
"EM assigns a probability distribution to each instance which
indicates the probability of it belonging to each of the clusters. "
Is this complex output really what you want?
It also selects a number of clusters for you (unless you constrain that number).
In weka 3.7 you can use the unsupervised attribute filter "ClusterMembership" in the Preprocess dialog to replace your dataset with a result of the cluster assignments. You need to select one reference attribute, though. By default it selects the last one. This creates hard-to -interpret output.

Speedy test on R data frame to see if row values in one column are inside another column in the data frame

I have a data frame of marketing data with 22k records and 6 columns, 2 of which are of interest.
Variable
FO.variable
Here's a link with the dput output of a sample of the dataframe: http://dpaste.com/2SJ6DPX
Please let me know if there's a better way of sharing this data.
All I want to do is create an additional binary keep column which should be:
1 if FO.variable is inside Variable
0 if FO.Variable is not inside Variable
Seems like a simple thing...in Excel I would just add another column with an "if" formula and then paste the formula down. I've spent the past hours trying to get this and R and failing.
Here's what I've tried:
Using grepl for pattern matching. I've used grepl before but this time I'm trying to pass a column instead of a string. My early attempts failed because I tried to force grepl and ifelse resulting in grepl using the first value in the column instead of the entire thing.
My next attempt was to use transform and grep based off another post on SO. I didn't think this would give me my exact answer but I figured it would get me close enough for me to figure it out from there...the code ran for a while than errored because invalid subscript.
transform(dd, Keep = FO.variable[sapply(variable, grep, FO.variable)])
My next attempt was to use str_detect, but I don't think this is the right approach because I want the row level value and I think 'any' will literally use any value in the vector?
kk <- sapply(dd$variable, function(x) any(sapply(dd$FO.variable, str_detect, string = x)))
EDIT: Just tried a for loop. I would prefer a vectorized approach but I'm pretty desperate at this point. I haven't used for-loops before as I've avoided them and stuck to other solutions. It doesn't seem to be working quite right not sure if I screwed up the syntax:
for(i in 1:nrow(dd)){
if(dd[i,4] %in% dd[i,2])
dd$test[i] <- 1
}
As I mentioned, my ideal output is an additional column with 1 or 0 if FO.variable was inside variable. For example, the first three records in the sample data would be 1 and the 4th record would be zero since "Direct/Unknown" is not within "Organic Search, System Email".
A bonus would be if a solution could run fast. The apply options were taking a long, long time perhaps because they were looping over every iteration across both columns?
This turned out to not nearly be as simple as I would of thought. Or maybe it is and I'm just a dunce. Either way, I appreciate any help on how to best approach this.
I read the data
df = dget("http://dpaste.com/2SJ6DPX.txt")
then split the 'variable' column into its parts and figured out the lengths of each entry
v = strsplit(as.character(df$variable), ",", fixed=TRUE)
len = lengths(v) ## sapply(v, length) in R-3.1.3
Then I unlisted v and created an index that maps the unlisted v to the row from which it came from
uv = unlist(v)
idx = rep(seq_along(v), len)
Finally, I found the indexes for which uv was equal to its corresponding entry in FO.variable
test = (uv == as.character(df$FO.variable)[idx])
df$Keep = FALSE
df$Keep[ idx[test] ] = TRUE
Or combined (it seems more useful to return the logical vector than the modified data.frame, which one could obtain with dd$Keep = f0(dd))
f0 = function(dd) {
v = strsplit(as.character(dd$variable), ",", fixed=TRUE)
len = lengths(v)
uv = unlist(v)
idx = rep(seq_along(v), len)
keep = logical(nrow(dd))
keep[ idx[uv == as.character(dd$FO.variable)[idx]] ] = TRUE
keep
}
(This could be made faster using the fact that the columns are factors, but maybe that's not intentional?) Compared with (the admittedly simpler and easier to understand)
f1 = function(dd)
mapply(grepl, dd$FO.variable, dd$variable, fixed=TRUE)
f1a = function(dd)
mapply(grepl, as.character(dd$FO.variable),
as.character(dd$variable), fixed=TRUE)
f2 = function(dd)
apply(dd, 1, function(x) grepl(x[4], x[2], fixed=TRUE))
with
> library(microbenchmark)
> identical(f0(df), f1(df))
[1] TRUE
> identical(f0(df), unname(f2(df)))
[1] TRUE
> microbenchmark(f0(df), f1(df), f1a(df), f2(df))
Unit: microseconds
expr min lq mean median uq max neval
f0(df) 57.559 64.6940 70.26804 69.4455 74.1035 98.322 100
f1(df) 573.302 603.4635 625.32744 624.8670 637.1810 766.183 100
f1a(df) 138.527 148.5280 156.47055 153.7455 160.3925 246.115 100
f2(df) 494.447 518.7110 543.41201 539.1655 561.4490 677.704 100
Two subtle but important additions during the development of the timings were to use fixed=TRUE in the regular expression, and to coerce the factors to character.
I would go with a simple mapply in your case, as you correctly said, by row operations will be very slow. Also, (as suggested by Martin) setting fixed = TRUE and apriori converting to character will significantly improve performance.
transform(dd, Keep = mapply(grepl,
as.character(FO.variable),
as.character(variable),
fixed = TRUE))
# VisitorIDTrue variable value FO.variable FO.value Keep
# 22 44888657 Direct / Unknown,Organic Search 1 Direct / Unknown 1 TRUE
# 2 44888657 Direct / Unknown,System Email 1 Direct / Unknown 1 TRUE
# 6 44888657 Direct / Unknown,TV 1 Direct / Unknown 1 TRUE
# 10 44888657 Organic Search,System Email 1 Direct / Unknown 1 FALSE
# 18 44888657 Organic Search,TV 1 Direct / Unknown 1 FALSE
# 14 44888657 System Email,TV 1 Direct / Unknown 1 FALSE
# 24 44888657 Direct / Unknown,Organic Search 1 Organic Search 1 TRUE
# 4 44888657 Direct / Unknown,System Email 1 Organic Search 1 FALSE
...
Here is a data.table approach that I think is very similar in spirit to Martin's:
require(data.table)
dt <- data.table(df)
dt[,`:=`(
fch = as.character(FO.variable),
rn = 1:.N
)]
dt[,keep:=FALSE]
dtvars <- dt[,strsplit(as.character(variable),',',fixed=TRUE),by=rn]
setkey(dt,rn,fch)
dt[dtvars,keep:=TRUE]
dt[,c("fch","rn"):=NULL]
The idea is to
identify all pairs of rn & variable (saved in dtvars) and
see which of these pairs match with rn & F0.variable pairs (in the original table, dt).

Calculating the distance between characters

Problem: I have a large number of scanned documents that are linked to the wrong records in a database. Each image has the correct ID on it somewhere that says where it belongs in the db.
I.E. A DB row could be:
| user_id | img_id | img_loc |
| 1 | 1 | /img.jpg|
img.jpg would have the user_id (1) on the image somewhere.
Method/Solution: Loop through the database. Pull the image text in to a variable with OCR and check if user_id is found anywhere in the variable. If not, flag the record/image in a log, if so do nothing and move on.
My example is simple, in the real world I have a guarantee that user_id wouldn't accidentally show up on the wrong form (it is of a specific format that has its own significance)
Right now it is working. However, it is incredibly strict. If you've worked with OCR you understand how fickle it can be. Sometimes a 7 = 1 or a 9 = 7, etc. The result is a large number of false positives. Especially among images with low quality scans.
I've addressed some of the image quality issues with some processing on my side - increase image size, adjust the black/white threshold and had satisfying results. I'd like to add the ability for the prog to recognize, for example, that "81*7*23103" is not very far from "81*9*23103"
The only way I know how to do that is to check for strings >= to the length of what I'm looking for. Calculate the distance between each character, calc an average and give it a limit on what is a good average.
Some examples:
Ex 1
81723103 - Looking for this
81923103 - Found this
--------
00200000 - distances between characters
0 + 0 + 2 + 0 + 0 + 0 + 0 + 0 = 2
2/8 = .25 (pretty good match. 0 = perfect)
Ex 2
81723103 - Looking
81158988 - Found
--------
00635885 - distances
0 + 0 + 6 + 3 + 5 + 8 + 8 + 5 = 35
35/8 = 4.375 (Not a very good match. 9 = worst)
This way I can tell it "Flag the bottom 30% only" and dump anything with an average distance > 6.
I figure I'm reinventing the wheel and wanted to share this for feedback. I see a huge increase in run time and a performance hit doing all these string operations over what I'm currently doing.

read table with spaces in one column

I am attempting to extract tables from very large text files (computer logs). Dickoa provided very helpful advice to an earlier question on this topic here: extracting table from text file
I modified his suggestion to fit my specific problem and posted my code at the link above.
Unfortunately I have encountered a complication. One column in the table contains spaces. These spaces are generating an error when I try to run the code at the link above. Is there a way to modify that code, or specifically the read.table function to recognize the second column below as a column?
Here is a dummy table in a dummy log:
> collect.models(, adjust = FALSE)
model npar AICc DeltaAICc weight Deviance
5 AA(~region + state + county + city)BB(~region + state + county + city)CC(~1) 17 11111.11 0.0000000 5.621299e-01 22222.22
4 AA(~region + state + county)BB(~region + state + county)CC(~1) 14 22222.22 0.0000000 5.621299e-01 77777.77
12 AA(~region + state)BB(~region + state)CC(~1) 13 33333.33 0.0000000 5.621299e-01 44444.44
12 AA(~region)BB(~region)CC(~1) 6 44444.44 0.0000000 5.621299e-01 55555.55
>
> # the three lines below count the number of errors in the code above
Here is the R code I am trying to use. This code works if there are no spaces in the second column, the model column:
my.data <- readLines('c:/users/mmiller21/simple R programs/dummy.log')
top <- '> collect.models\\(, adjust = FALSE)'
bottom <- '> # the three lines below count the number of errors in the code above'
my.data <- my.data[grep(top, my.data):grep(bottom, my.data)]
x <- read.table(text=my.data, comment.char = ">")
I believe I must use the variables top and bottom to locate the table in the log because the log is huge, variable and complex. Also, not every table contains the same number of models.
Perhaps a regex expression could be used somehow taking advantage of the AA and the CC(~1) present in every model name, but I do not know how to begin. Thank you for any help and sorry for the follow-up question. I should have used a more realistic example table in my initial question. I have a large number of logs. Otherwise I could just extract and edit the tables by hand. The table itself is an odd object which I have only ever been able to export directly with capture.output, which would probably still leave me with the same problem as above.
EDIT:
All spaces seem to come right before and right after a plus sign. Perhaps that information can be used here to fill the spaces or remove them.
try inserting my.data$model <- gsub(" *\\+ *", "+", my.data$model) before read.table
my.data <- my.data[grep(top, my.data):grep(bottom, my.data)]
my.data$model <- gsub(" *\\+ *", "+", my.data$model)
x <- read.table(text=my.data, comment.char = ">")