[R] Help with merge function

[Rui Barradas]

Hello,

I don't understand the question, what range? I've just changed the 'all' 
argument to 'all.y', without doing anything special to the variables.
Can you explain what you mean?

Rui Barradas


Em 26-04-2013 19:30, Catarina Ferreira escreveu:
> Hello, Thank you for your help. However the dataframes I gave you were only
> examples, the actual dataframes are very big. Does this mean I have to
> write every range of data for each variable??
>
>
> On Fri, Apr 26, 2013 at 2:25 PM, Rui Barradas <ruipbarradas at sapo.pt> wrote:
>
>> Hello,
>>
>> The following seems to do the trick.
>>
>>
>>
>> x1 <-
>> structure(list(State_prov = c("Nova Scotia", "Nova Scotia", "Nova Scotia"
>> ), Shape_name = c("Annapolis", "Antigonish", "Gly"), bob2009 = c(0L,
>> 0L, NA), bob2010 = c(0L, 0L, NA), bob2011 = c(1L, 0L, NA)), .Names =
>> c("State_prov",
>> "Shape_name", "bob2009", "bob2010", "bob2011"), class = "data.frame",
>> row.names = c(NA,
>> -3L))
>>
>> x2 <-
>> structure(list(FID = 0:2, State_prov = c("Nova Scotia", "Nova Scotia",
>> "Nova Scotia"), Shape_name = c("Annapolis", "Antigonish", "Gly"
>> ), bob2009 = c(0L, 0L, 0L), bob2010 = c(0L, 0L, 0L), coy2009 = c(10L,
>> 1L, 1L)), .Names = c("FID", "State_prov", "Shape_name", "bob2009",
>> "bob2010", "coy2009"), class = "data.frame", row.names = c(NA,
>> -3L))
>>
>> x3  <- merge(x1, x2, all.y = TRUE)
>>
>>
>>
>> Note also that since by = intersect(names(x1), names(x2)), you really
>> don't need it, it's the default behavior.
>>
>> Hope this helps,
>>
>> Rui Barradas
>>
>> Em 26-04-2013 18:10, Catarina Ferreira escreveu:
>>
>>   Dear all,
>>>
>>> I'm trying to merge 2 dataframes, but I'm not being entirely successful
>>> and
>>> I can't understand why.
>>>
>>> Dataframe x1
>>>
>>> State_prov     Shape_name   bob2009   bob 2010   bob2011
>>> Nova Scotia    Annapolis         0                  0              1
>>> Nova Scotia    Antigonish        0                  0              0
>>> Nova Scotia    Gly                   NA               NA             NA
>>>
>>> Dataframe x2 - has 20000 rows and 193 variables, contains one important
>>> field which is "FID" that is a link to a shapefile (this is not in x1) and
>>> shares common columns with x1, like this:
>>>
>>> FID     State_prov     Shape_name   bob2009   bob 2010  coy 2009
>>>    0        Nova Scotia    Annapolis         0
>>> 0              10
>>>    1        Nova Scotia    Antigonish        0
>>> 0              1
>>>    2        Nova Scotia    Gly                   0
>>> 0              1
>>>
>>> So when I do
>>>
>>> x3  <- merge(x1, x2, by=intersect(names(x1), names(x2)), all=TRUE)
>>>
>>> it should do the trick. The thing is that it works for the columns (it
>>> adds
>>> all the new columns not common to both dataframes), but it also adds the
>>> rows. This is what I get (x3):
>>>
>>> FID     State_prov     Shape_name   bob2009   bob 2010  coy 2009   bob2011
>>>    0        Nova Scotia    Annapolis         0
>>> 0              10            NA
>>>    NA      Nova Scotia    Annapolis         NA               NA          NA
>>>               1
>>>    1        Nova Scotia    Antigonish        0
>>> 0              1               NA
>>> NA      Nova Scotia    Antigonish        NA               NA          NA
>>>               0
>>>    2        Nova Scotia    Gly                   0
>>> 0              1               NA
>>> NA      Nova Scotia    Gly                   NA               NA
>>> NA             NA
>>>
>>> What I want to get is a true merge, like this:
>>>
>>> FID     State_prov     Shape_name   bob2009   bob 2010  coy 2009   bob2011
>>>    0        Nova Scotia    Annapolis         0
>>> 0              10            1
>>>    1        Nova Scotia    Antigonish        0
>>> 0              1               0
>>>    2        Nova Scotia    Gly                   0
>>> 0              1               NA
>>>
>>> Can anybody please help me to understand what I'm doing wrong.
>>> Any help will be much appreciated!!
>>>
>>>
>>>
>
>