natbusa

DROP TABLE followers;
CREATE TABLE followers (
      followed_id text,
      follower_id text,
      created timestamp,
      messages_count int,
      likes_count int,
      PRIMARY KEY ((followed_id, follower_id))
);

natbusa

# the following will work (followed_id,follower_id is a partition key)#

cqlsh:test> select * from followers where followed_id='123' and follower_id='567';

 followed_id | follower_id | created                  | likes_count | messages_count
-------------+-------------+--------------------------+-------------+----------------
         123 |         567 | 2011-02-03 05:05:00+0100 |           5 |              2

# the following will not work (followed_id,follower_id is a partition key)#

natbusa

DROP TABLE followers;
CREATE TABLE followers (
      followed_id text,
      follower_id text,
      created timestamp,
      messages_count int,
      likes_count int,
      PRIMARY KEY (followed_id, follower_id)
);

natbusa

CREATE TABLE table1 (
  a1 text,
  a2 text,
  b1 text,
  b2 text,
  c1 text,
  c2 text,
  PRIMARY KEY ( (a1, a2), b1, b2 )
);

natbusa

library("ggplot2")

logfile = "
   task a,2,9
   task b,3,8
   task c,1,4
   task d,5,12
"

# read in the sample logfile in a data frame

natbusa

library("ggplot2")

#sample logfile
logfile = "
   task a,2013-10-10 11:16:16,2013-10-10 11:21:16
   task b,2013-10-10 11:15:16,2013-10-10 11:18:45
   task c,2013-10-10 11:20:20,2013-10-10 11:21:00
   task d,2013-10-10 11:14:23,2013-10-10 11:19:30
"

natbusa

library("ggplot2")

# calculate a 1000 iterations for a selection of four sample from 
# a normal population N(0,1)

mean.statistics= sapply(1:1000, function(x) {sum(rnorm(4,0,1))/4})

#base plot, but no functions

p = ggplot(data.frame(mean.statistics), aes(mean.statistics)) +  xlim(-2,2)

natbusa

> mean.muhat = mean(mean.statistics)
> mean.muhat
[1] 0.007315414
> 
> mean.sehat = sd(mean.statistics)
> mean.sehat
[1] 0.4974518
> 
> # mean =  0.007 +- 2*0.5

natbusa

library("MASS")

write.csv(Cars93, 'cars93.csv')

natbusa

library('ggplot2')

#basics

3*4
2^3
1/2 + 1/2*sqrt(5)

#those two are identical
(1+2+3+4)/4