Not sure why I'm having a difficult time with this, it seems so simple considering it's fairly easy to do in R or pandas. I wanted to avoid using pandas though since I'm dealing with a lot of data, and I believe toPandas() loads all the data into the driver’s memory in pyspark.
I have 2 dataframes: df1 and df2. I want to filter df1 (remove all rows) where df1.userid = df2.userid AND df1.group = df2.group. I wasn't sure if I should use filter(), join(), or sql For example:
df1:
+------+----------+--------------------+
|userid| group | all_picks |
+------+----------+--------------------+
| 348| 2|[225, 2235, 2225] |
| 567| 1|[1110, 1150] |
| 595| 1|[1150, 1150, 1150] |
| 580| 2|[2240, 2225] |
| 448| 1|[1130] |
+------+----------+--------------------+
df2:
+------+----------+---------+
|userid| group | pick |
+------+----------+---------+
| 348| 2| 2270|
| 595| 1| 2125|
+------+----------+---------+
Result I want:
+------+----------+--------------------+
|userid| group | all_picks |
+------+----------+--------------------+
| 567| 1|[1110, 1150] |
| 580| 2|[2240, 2225] |
| 448| 1|[1130] |
+------+----------+--------------------+
EDIT:
I've tried many join() and filter() functions, I believe the closest I got was:
cond = [df1.userid == df2.userid, df2.group == df2.group]
df1.join(df2, cond, 'left_outer').select(df1.userid, df1.group, df1.all_picks) # Result has 7 rows
I tried a bunch of different join types, and I also tried different
cond values:
cond = ((df1.userid == df2.userid) & (df2.group == df2.group)) # result has 7 rows
cond = ((df1.userid != df2.userid) & (df2.group != df2.group)) # result has 2 rows
However, it seems like the joins are adding additional rows, rather than deleting.
I'm using python 2.7 and spark 2.1.0
Left anti join is what you're looking for:
df1.join(df2, ["userid", "group"], "leftanti")
but the same thing can be done with left outer join:
(df1
.join(df2, ["userid", "group"], "leftouter")
.where(df2["pick"].isNull())
.drop(df2["pick"]))
Related
I am trying to concatonate multiple columns to just one column, but only if the column name is in a list.
so issue = {'a','b','c'} is my list and would need to concatonate it as issue column with ; seperator.
I have tried:
1.
df_issue = df.withColumn('issue', concat_ws(';',map_values(custom.({issue}))))
Which returns invalid syntax error
2.
df_issue = df.withColumn('issue', lit(issue))
this just returnd a b c and not their value
Thank you
I have tried:
1.
df_issue = df.withColumn('issue', concat_ws(';',map_values(custom.({issue}))))
Which returns invalid syntax error
2.
df_issue = df.withColumn('issue', lit(issue))
this just returnd a b c and not their value
Thank you
You can simply use concat_ws:
from pyspark.sql import functions as F
columns_to_concat = ['a', 'b', 'c']
df.withColumn('issue', F.concat_ws(';', *columns_to_concat))
So, if your input DataFrame is:
+---+---+---+----------+----------+-----+
| a| b| c| date1| date2|value|
+---+---+---+----------+----------+-----+
| k1| k2| k3|2022-11-11|2022-11-14| 5|
| k4| k5| k6|2022-11-15|2022-11-19| 5|
| k7| k8| k9|2022-11-15|2022-11-19| 5|
+---+---+---+----------+----------+-----+
The previous code will produce:
+---+---+---+----------+----------+-----+--------+
| a| b| c| date1| date2|value| issue|
+---+---+---+----------+----------+-----+--------+
| k1| k2| k3|2022-11-11|2022-11-14| 5|k1;k2;k3|
| k4| k5| k6|2022-11-15|2022-11-19| 5|k4;k5;k6|
| k7| k8| k9|2022-11-15|2022-11-19| 5|k7;k8;k9|
+---+---+---+----------+----------+-----+--------+
I have an import query (table a) and an imported Excel file (table b) with records I am trying to match it up with.
I am looking for a method to replicate this type of SQL in M:
SELECT a.loc_id, a.other_data, b.stk
FROM a INNER JOIN b on a.loc_id BETWEEN b.from_loc AND b.to_loc
Table A
| loc_id | other data |
-------------------------
| 34A032B1 | ... |
| 34A3Z011 | ... |
| 3DD23A41 | ... |
Table B
| stk | from_loc | to_loc |
--------------------------------
| STKA01 | 34A01 | 34A30ZZZ |
| STKA02 | 34A31 | 34A50ZZZ |
| ... | ... | ... |
Goal
| loc_id | other data | stk |
----------------------------------
| 34A032B1 | ... | STKA01 |
| 34A3Z011 | ... | STKA02 |
| 3DD23A41 | ... | STKD01 |
All of the other queries I can find along these lines use numbers, dates, or times in the BETWEEN clause, and seem to work by exploding the (from, to) range into all possible values and then filtering out the extra rows. However I need to use string comparisons, and exploding those into all possible values would be unfeasable.
Between all the various solutions I could find, the closest I've come is to add a custom column on table a:
Table.SelectRows(
table_b,
(a) => Value.Compare([loc_id], table_b[from_loc]) = 1
and Value.Compare([loc_id], table_b[to_loc]) = -1
)
This does return all the columns from table_b, however, when expanding the column, the values are all null.
This is not very specific "After 34A01 could be any string..." in trying to figure out how your series progresses.
But maybe you can just test for how a value "sorts" using the native sorting function in PQ.
add custom column with table.Select Rows:
= try Table.SelectRows(TableB, (t)=> t[from_loc]<=[loc_id] and t[to_loc] >= [loc_id])[stk]{0} otherwise null
To reproduce with your examples:
let
TableB=Table.FromColumns(
{{"STKA01","STKA02"},
{"34A01","34A31"},
{"34A30ZZZ","34A50ZZZ"}},
type table[stk=text,from_loc=text,to_loc=text]),
TableA=Table.FromColumns(
{{"34A032B1","34A3Z011","3DD23A41"},
{"...","...","..."}},
type table[loc_id=text, other data=text]),
//determine where it sorts and return the stk
#"Added Custom" = Table.AddColumn(#"TableA", "stk", each
try Table.SelectRows(TableB, (t)=> t[from_loc]<=[loc_id] and t[to_loc] >= [loc_id])[stk]{0} otherwise null)
in
#"Added Custom"
Note: if the above algorithm is too slow, there may be faster methods of obtaining these results
I am trying to use Django StrIndex to find all rows with the value a substring of a given string.
Eg:
my table contains:
+----------+------------------+
| user | domain |
+----------+------------------+
| spam1 | spam.com |
| badguy+ | |
| | protonmail.com |
| spammer | |
| | spamdomain.co.uk |
+----------+------------------+
but the query
SpamWord.objects.annotate(idx=StrIndex(models.Value('xxxx'), 'user')).filter(models.Q(idx__gt=0) | models.Q(domain='spamdomain.co.uk')).first()
matches <SpamWord: *#protonmail.com>
The query it is SELECT `spamwords`.`id`, `spamwords`.`user`, `spamwords`.`domain`, INSTR('xxxx', `spamwords`.`user`) AS `idx` FROM `spamwords` WHERE (INSTR('xxxx', `spamwords`.`user`) > 0 OR `spamwords`.`domain` = 'spamdomain.co.uk')
It should be <SpamWord: *#spamdomain.co.uk>
this is happening because
INSTR('xxxx', '') => 1
(and also INSTR('xxxxasd', 'xxxx') => 1, which it is correct)
How can I write this query in order to get entry #5 (spamdomain.co.uk)?
The order of the parameters of StrIndex [Django-doc] is swapped. The first parameter is the haystack, the string in which you search, and the second one is the needle, the substring you are looking for.
You thus can annotate with:
from django.db.models import Q, Value
SpamWord.objects.annotate(
idx=StrIndex('user', Value('xxxx'))
).filter(
Q(idx__gt=0) | Q(domain='spamdomain.co.uk')
).first()
Just filter rows where user is empty:
(~models.Q(user='') & models.Q(idx__gt=0)) | models.Q(domain='spamdomain.co.uk')
Let's say you have a Spark dataframe with multiple columns and you want to return the rows where the columns contains specific characters. Specifically you want to return the rows where at least one of the fields contains ( ) , [ ] % or +.
What is the proper syntax in case you want to use Spark SQL rlike function?
import spark.implicits._
val dummyDf = Seq(("John[", "Ha", "Smith?"),
("Julie", "Hu", "Burol"),
("Ka%rl", "G", "Hu!"),
("(Harold)", "Ju", "Di+")
).toDF("FirstName", "MiddleName", "LastName")
dummyDf.show()
+---------+----------+--------+
|FirstName|MiddleName|LastName|
+---------+----------+--------+
| John[| Ha| Smith?|
| Julie| Hu| Burol|
| Ka%rl| G| Hu!|
| (Harold)| Ju| Di+|
+---------+----------+--------+
Expected Output
+---------+----------+--------+
|FirstName|MiddleName|LastName|
+---------+----------+--------+
| John[| Ha| Smith?|
| Ka%rl| G| Hu!|
| (Harold)| Ju| Di+|
+---------+----------+--------+
My few attempts returns errors or not what expected even when I try to do it just for searching (.
I know that I could use the simple like construct multiple times, but I am trying to figure out to do it in a more concise way with regex and Spark SQL.
You can try this using rlike method:
dummyDf.show()
+---------+----------+--------+
|FirstName|MiddleName|LastName|
+---------+----------+--------+
| John[| Ha| Smith?|
| Julie| Hu| Burol|
| Ka%rl| G| Hu!|
| (Harold)| Ju| Di+|
| +Tim| Dgfg| Ergf+|
+---------+----------+--------+
val df = dummyDf.withColumn("hasSpecial",lit(false))
val result = df.dtypes
.collect{ case (dn, dt) => dn }
.foldLeft(df)((accDF, c) => accDF.withColumn("hasSpecial", col(c).rlike(".*[\\(\\)\\[\\]%+]+.*") || col("hasSpecial")))
result.filter(col("hasSpecial")).show(false)
Output:
+---------+----------+--------+----------+
|FirstName|MiddleName|LastName|hasSpecial|
+---------+----------+--------+----------+
|John[ |Ha |Smith? |true |
|Ka%rl |G |Hu! |true |
|(Harold) |Ju |Di+ |true |
|+Tim |Dgfg |Ergf+ |true |
+---------+----------+--------+----------+
You can also drop the hasSpecial column if you want.
Try this .*[()\[\]%\+,.]+.*
.* all character zero or more times
[()[]%+,.]+ all characters inside bracket 1 or more times
.* all character zero or more times
I have a DataFrame inside of a function:
using DataFrames
myservs = DataFrame(serverName = ["elmo", "bigBird", "Oscar", "gRover", "BERT"],
ipAddress = ["12.345.6.7", "12.345.6.8", "12.345.6.9", "12.345.6.10", "12.345.6.11"])
myservs
5x2 DataFrame
| Row | serverName | ipAddress |
|-----|------------|---------------|
| 1 | "elmo" | "12.345.6.7" |
| 2 | "bigBird" | "12.345.6.8" |
| 3 | "Oscar" | "12.345.6.9" |
| 4 | "gRover" | "12.345.6.10" |
| 5 | "BERT" | "12.345.6.11" |
How can I write the function to take a single parameter called server, case-insensitive match the server parameter in the myservs[:serverName] DataArray, and return the match's corresponding ipAddress?
In R this can be done by using
myservs$ipAddress[grep("server", myservs$serverName, ignore.case = T)]
I don't want it to matter if someone uses ElMo or Elmo as the server, or if the serverName is saved as elmo or ELMO.
I referenced how to accomplish the task in R and tried to do it using the DataFrames pkg, but I only did this because I'm coming from R and am just learning Julia. I asked a lot of questions from coworkers and the following is what we came up with:
This task is much cleaner if I was to stop thinking in terms of
vectors in R. Julia runs plenty fast iterating through a loop.
Even still, looping wouldn't be the best solution here. I was told to look into
Dicts (check here for an example). Dict(), zip(), haskey(), and
get() blew my mind. These have many applications.
My solution doesn't even need to use the DataFrames pkg, but instead
uses Julia's Matrix and Array data representations. By using let
we keep the global environment clutter free and the server name/ip
list stays hidden from view to those who are only running the
function.
In the sample code, I'm recreating the server matrix every time, but in reality/practice I'll have a permission restricted delimited file that gets read every time. This is OK for now since the delimited files are small, but this may not be efficient or the best way to do it.
# ONLY ALLOW THE FUNCTION TO BE SEEN IN THE GLOBAL ENVIRONMENT
let global myIP
# SERVER MATRIX
myservers = ["elmo" "12.345.6.7"; "bigBird" "12.345.6.8";
"Oscar" "12.345.6.9"; "gRover" "12.345.6.10";
"BERT" "12.345.6.11"]
# SERVER DICT
servDict = Dict(zip(pmap(lowercase, myservers[:, 1]), myservers[:, 2]))
# GET SERVER IP FUNCTION: INPUT = SERVER NAME; OUTPUT = IP ADDRESS
function myIP(servername)
sn = lowercase(servername)
get(servDict, sn, "That name isn't in the server list.")
end
end
# Test it out
myIP("SLIMEY")
#>"That name isn't in the server list."
myIP("elMo")
#>"12.345.6.7"
Here's one way:
julia> using DataFrames
julia> myservs = DataFrame(serverName = ["elmo", "bigBird", "Oscar", "gRover", "BERT"],
ipAddress = ["12.345.6.7", "12.345.6.8", "12.345.6.9", "12.345.6.10", "12.345.6.11"])
5x2 DataFrames.DataFrame
| Row | serverName | ipAddress |
|-----|------------|---------------|
| 1 | "elmo" | "12.345.6.7" |
| 2 | "bigBird" | "12.345.6.8" |
| 3 | "Oscar" | "12.345.6.9" |
| 4 | "gRover" | "12.345.6.10" |
| 5 | "BERT" | "12.345.6.11" |
julia> grep{T <: String}(pat::String, dat::DataArray{T}, opts::String = "") = Bool[isna(d) ? false : ismatch(Regex(pat, opts), d) for d in dat]
grep (generic function with 2 methods)
julia> myservs[:ipAddress][grep("bigbird", myservs[:serverName], "i")]
1-element DataArrays.DataArray{ASCIIString,1}:
"12.345.6.8"
EDIT
This grep works faster on my platform.
julia> function grep{T <: String}(pat::String, dat::DataArray{T}, opts::String = "")
myreg = Regex(pat, opts)
return convert(Array{Bool}, map(d -> isna(d) ? false : ismatch(myreg, d), dat))
end