Write xts/zoo object to csv with index

Question

``` > library(PerformanceAnalytics) > data(managers) > class(managers) [1] "xts" "zoo" > head(managers) HAM1 HAM2 HAM3 HAM4 HAM5 HAM6 EDHEC LS EQ SP500 TR US 10Y TR US 3m TR 1996-01-31 0.0074 NA 0.0349 0.0222 NA NA NA 0.0340 0.00380 0.00456 1996-02-29 0.0193 NA 0.0351 0.0195 NA NA NA 0.0093 -0.03532 0.00398 1996-03-31 0.0155 NA 0.0258 -0.0098 NA NA NA 0.0096 -0.01057 0.00371 1996-04-30 -0.0091 NA 0.0449 0.0236 NA NA NA 0.0147 -0.01739 0.00428 1996-05-31 0.0076 NA 0.0353 0.0028 NA NA NA 0.0258 -0.00543 0.00443 1996-06-30 -0.0039 NA -0.0303 -0.0019 NA NA NA 0.0038 0.01507 0.00412 ``` When I try to export this object to csv using `write.csv`, the date indices are not exported. How do I enforce the first column of the csv output to be the date indices? ``` "","HAM1","HAM2","HAM3","HAM4","HAM5","HAM6","EDHEC LS EQ","SP500 TR","US 10Y TR","US 3m TR" "1",0.0074,NA,0.0349,0.0222,NA,NA,NA,0.034,0.0038,0.00456 "2",0.0193,NA,0.0351,0.0195,NA,NA,NA,0.0093,-0.03532,0.00398 "3",0.0155,NA,0.0258,-0.…

Accepted Answer

The date does show up. Here is a reproducible example:

```
dfA = read.table(textConnection('row.name HAM1    HAM2    HAM3    HAM4    HAM5    HAM6 "EDHEC LS EQ"  SP500 "TR US 10Y" "TR US 3m TR"
1996-01-31  0.0074      NA  0.0349  0.0222      NA      NA          NA  0.034000   0.00380  0.00456
1996-02-29  0.0193      NA  0.0351  0.0195      NA      NA          NA  0.009300  -0.03532  0.00398
1996-03-31  0.0155      NA  0.0258 -0.0098      NA      NA          NA  0.009600  -0.01057  0.00371
1996-04-30 -0.0091      NA  0.0449  0.0236      NA      NA          NA  0.014700  -0.01739  0.00428
1996-05-31  0.0076      NA  0.0353  0.0028      NA      NA          NA  0.025800  -0.00543  0.00443
1996-06-30 -0.0039      NA -0.0303 -0.0019      NA      NA          NA  0.003800   0.01507  0.00412
1996-07-31 -0.0231      NA -0.0337 -0.0446      NA      NA          NA -0.044200  -0.00100  0.00454
1996-08-31  0.0395 -0.0001  0.0461  0.0351      NA      NA          NA  0.021100  -0.00448  0.00451
1996-09-30  0.0147  0.1002  0.0653  0.0757      NA      NA          NA  0.056300   0.02229  0.00470
1996-10-31  0.0288  0.0338  0.0395 -0.0180      NA      NA          NA  0.027600   0.02869  0.00428'), header = TRUE)

row.names(dfA) = as.Date(dfA$row.name, format = '%Y-%m-%d')
dfA$row.name = NULL
write.csv(dfA, file = 'delete.txt', row.names = TRUE)
```

Update

`zoo` will lead to similar handling:

```
library(zoo)
zooA = as.zoo(dfA, order.by = row.names(dfA))
write.csv(zooA, file = 'delete.txt', row.names = TRUE)
```

"","HAM1","HAM2","HAM3","HAM4","HAM5","HAM6","EDHEC.LS.EQ","SP500","TR.US.10Y","TR.US.3m.TR" "1996-01-31",0.0074,NA,0.0349,0.0222,NA,NA,NA,0.034,0.0038,0.00456 "1996-02-29",0.0193,NA,0.0351,0.0195,NA,NA,NA,0.0093,-0.03532,0.00398 "1996-03-31",0.0155,NA,0.0258,-0.0098,NA,NA,NA,0.0096,-0.01057,0.00371 "1996-04-30",-0.0091,NA,0.0449,0.0236,NA,NA,NA,0.0147,-0.01739,0.00428 "1996-05-31",0.0076,NA,0.0353,0.0028,NA,NA,NA,0.0258,-0.00543,0.00443 "1996-06-30",-0.0039,NA,-0.0303,-0.0019,NA,NA,NA,0.0038,0.01507,0.00412 "1996-07-31",-0.0231,NA,-0.0337,-0.0446,NA,NA,NA,-0.0442,-0.001,0.00454 "1996-08-31",0.0395,-1e-04,0.0461,0.0351,NA,NA,NA,0.0211,-0.00448,0.00451 "1996-09-30",0.0147,0.1002,0.0653,0.0757,NA,NA,NA,0.0563,0.02229,0.0047 "1996-10-31",0.0288,0.0338,0.0395,-0.018,NA,NA,NA,0.0276,0.02869,0.00428

Update 2

Turns out that OP has an `xts` object that has an`index` attribute rather than a `rownames` attribute, which can be written out using a call to `write.zoo` rather than `write.csv` (which looks for `rownames`).

Write xts/zoo object to csv with index

Solution

Problem