# Dropmissing!() on a dataframe causes segfault

**URL:** <https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101>\
**Category:** General Usage\
**Created:** [September 22, 2020, 10:07pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101 "2020-09-22T22:07:47Z")\
**Posts on this page:** 9\
**Page:** 1

<div class="post-metadata">

**Author:** ![scone](https://avatars.discourse-cdn.com/v4/letter/s/b487fb/32.png) [@scone](https://discourse.julialang.org/u/scone)\
**Post date:** [September 22, 2020, 10:07pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/1 "2020-09-22T22:07:47Z")

</div>

I have code that was working just a week ago, and now when I get to the line with dropmissing!(df), I get this:

```julia
MethodError: Cannot `convert` an object of type Missing to an object of type Float64
Closest candidates are:
  convert(::Type{T}, ::T) where T<:Number at number.jl:6
  convert(::Type{T}, ::Number) where T<:Number at number.jl:7
  convert(::Type{T}, ::Base.TwicePrecision) where T<:Number at twiceprecision.jl:250
  ...
Stacktrace:
 [1] setindex!(::Array{Float64,1}, ::Missing, ::Int64) at ./array.jl:826
 [2] copyto!(::Array{Float64,1}, ::SentinelArrays.SentinelArray{Float64,1,Float64,Missing,SentinelArrays.ChainedVector{Float64,Array{Float64,1}}}) at ./multidimensional.jl:962
 [3] AbstractArray at ./array.jl:542 [inlined]
 [4] AbstractArray at ./boot.jl:432 [inlined]
 [5] convert at ./abstractarray.jl:15 [inlined]
 [6] disallowmissing(::SentinelArrays.SentinelArray{Float64,1,Float64,Missing,SentinelArrays.ChainedVector{Float64,Array{Float64,1}}}) at /home/efurtak/.julia/packages/Missings/notdc/src/Missings.jl:50
 [7] disallowmissing!(::DataFrame, ::Int64; error::Bool) at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/dataframe/dataframe.jl:1001
 [8] #disallowmissing!#177 at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/dataframe/dataframe.jl:1009 [inlined]
 [9] #disallowmissing!#180 at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/dataframe/dataframe.jl:1025 [inlined]
 [10] disallowmissing! at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/dataframe/dataframe.jl:1025 [inlined]
 [11] dropmissing!(::DataFrame, ::Colon; disallowmissing::Bool) at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/abstractdataframe.jl:877
 [12] dropmissing! at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/abstractdataframe.jl:876 [inlined] (repeats 2 times)
 [13] top-level scope at /run/media/efurtak/spindisk/oceano/oceano_met/code_explore_CDF_data/read_scrub_data.jl:24

julia> 
signal (11): Segmentation fault
in expression starting at none:0
jl_is_concrete_type at /buildworker/worker/package_linux64/build/src/julia.h:1230 [inlined]
jl_apply_tuple_type_v_ at /buildworker/worker/package_linux64/build/src/jltypes.c:1351 [inlined]
jl_apply_tuple_type_v at /buildworker/worker/package_linux64/build/src/jltypes.c:1364
arg_type_tuple at /buildworker/worker/package_linux64/build/src/gf.c:1772
jl_lookup_generic_ at /buildworker/worker/package_linux64/build/src/gf.c:2288 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2319
getmaxwidths at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/show.jl:175
unknown function (ip: 0x7f38731fbddd)
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
#_show#444 at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/show.jl:588
_show##kw at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/show.jl:564 [inlined]
#show#445 at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/show.jl:665 [inlined]
show##kw at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/show.jl:665 [inlined]
#show#460 at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/io.jl:56
unknown function (ip: 0x7f38731f8ca1)
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
show at /home/efurtak/.julia/packages/DataFrames/4ov0U/src/abstractdataframe/io.jl:56
#85 at /home/efurtak/.julia/packages/Atom/ipSjf/src/display/base.jl:56
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
#sprint#338 at ./strings/io.jl:105
sprint at ./strings/io.jl:101 [inlined]
macro expansion at /home/efurtak/.julia/packages/Atom/ipSjf/src/display/base.jl:56 [inlined]
render at /home/efurtak/.julia/packages/Media/ItEPc/src/system.jl:173
render′ at /home/efurtak/.julia/packages/Atom/ipSjf/src/display/errors.jl:119
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
wsitem at /home/efurtak/.julia/packages/Atom/ipSjf/src/workspace.jl:22
wsitem at /home/efurtak/.julia/packages/Atom/ipSjf/src/workspace.jl:19
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
#251 at /home/efurtak/.julia/packages/Atom/ipSjf/src/workspace.jl:8
iterate at ./generator.jl:47 [inlined]
collect_to! at ./array.jl:711 [inlined]
collect_to_with_first! at ./array.jl:689
_collect at ./array.jl:683
collect_similar at ./array.jl:607 [inlined]
map at ./abstractarray.jl:2072 [inlined]
workspace at /home/efurtak/.julia/packages/Atom/ipSjf/src/workspace.jl:8
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
handlemsg at /home/efurtak/.julia/packages/Atom/ipSjf/src/comm.jl:169
unknown function (ip: 0x7f388e5983c7)
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
jl_apply at /buildworker/worker/package_linux64/build/src/julia.h:1700 [inlined]
do_apply at /buildworker/worker/package_linux64/build/src/builtins.c:643
#31 at ./task.jl:358
unknown function (ip: 0x7f388e566add)
_jl_invoke at /buildworker/worker/package_linux64/build/src/gf.c:2145 [inlined]
jl_apply_generic at /buildworker/worker/package_linux64/build/src/gf.c:2323
jl_apply at /buildworker/worker/package_linux64/build/src/julia.h:1700 [inlined]
start_task at /buildworker/worker/package_linux64/build/src/task.c:687
unknown function (ip: (nil))
Allocations: 218692717 (Pool: 218637202; Big: 55515); GC: 167

```

I didn’t change any code or data, does anyone have any ideas what is causing this issue?

Thanks

---

<div class="post-metadata">

**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [September 22, 2020, 11:03pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/2 "2020-09-22T23:03:07Z")

</div>

Please file an issue for this with a minimum working example (including the CSV you got the data from, if possible.

What version of DataFrames are you on? Can you try updating all your packages and trying again?

---

<div class="post-metadata">

**Author:** ![nalimilan](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/nalimilan/32/147_2.png) [@nalimilan](https://discourse.julialang.org/u/nalimilan)\
**Post date:** [September 23, 2020, 11:57am UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/3 "2020-09-23T11:57:42Z")

</div>

In particular, the version of SentinelArrays you’re using is the most important information.

---

<div class="post-metadata">

**Author:** ![scone](https://avatars.discourse-cdn.com/v4/letter/s/b487fb/32.png) [@scone](https://discourse.julialang.org/u/scone)\
**Post date:** [September 23, 2020, 4:45pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/4 "2020-09-23T16:45:57Z")

</div>

Thanks for the replies. I thought it was up to date yesterday, but now I am not sure. I just updated again, and am still getting the same error without the segfault. The version is v0.21.7. I’ll try to put a small example together at some point today. Where/ how do I file an issue?

---

<div class="post-metadata">

**Author:** ![scone](https://avatars.discourse-cdn.com/v4/letter/s/b487fb/32.png) [@scone](https://discourse.julialang.org/u/scone)\
**Post date:** [September 23, 2020, 4:47pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/5 "2020-09-23T16:47:00Z")

</div>

Also, sorry I am not sure what SentinelArrays is, or how to check the version? It doesn’t seem to be an available package or one that I have installed.

---

<div class="post-metadata">

**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [September 23, 2020, 4:58pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/6 "2020-09-23T16:58:58Z")

</div>

can you show the results of `] st` in your REPL?

File an issue at github [here](https://github.com/JuliaData/DataFrames.jl/issues)!

---

<div class="post-metadata">

**Author:** ![scone](https://avatars.discourse-cdn.com/v4/letter/s/b487fb/32.png) [@scone](https://discourse.julialang.org/u/scone)\
**Post date:** [September 23, 2020, 5:05pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/7 "2020-09-23T17:05:36Z")

</div>

Here it is:

```julia
(@v1.4) pkg> st
Status `~/.julia/environments/v1.4/Project.toml`
  [c52e3926] Atom v0.12.21
  [336ed68f] CSV v0.7.7
  [8f4d0f93] Conda v1.4.1
  [a93c6f00] DataFrames v0.21.7
  [31c24e10] Distributions v0.23.12
  [5789e2e9] FileIO v1.4.3
  [5752ebe1] GMT v0.24.0
  [28b8d3ca] GR v0.48.0
  [0ef565a4] Geodesy v0.5.0
  [6218d12a] ImageMagick v1.1.6
  [4138dd39] JLD v0.10.0
  [494afd89] JavaCall v0.7.5
  [e5e0dc1b] Juno v0.8.4
  [47be7bcc] ORCA v0.5.0
  [3b7a836e] PGFPlots v3.3.2
  [8314cec4] PGFPlotsX v1.2.10
  [f0f68f2c] PlotlyJS v0.14.0
  [91a5bcdd] Plots v0.29.9
  [438e738f] PyCall v1.91.4
  [d330b81b] PyPlot v2.9.0
  [f2b01f46] Roots v1.0.5
  [60ddc479] StatPlots v0.9.2
  [f3b207a7] StatsPlots v0.14.13
  [61d0e4fa] Taro v0.8.2
  [fdbf4ff8] XLSX v0.7.3

```

---

<div class="post-metadata">

**Author:** ![scone](https://avatars.discourse-cdn.com/v4/letter/s/b487fb/32.png) [@scone](https://discourse.julialang.org/u/scone)\
**Post date:** [September 25, 2020, 7:33pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/8 "2020-09-25T19:33:50Z")

</div>

Update:

The segfault seems to end on its own, but I figured out that for some reason

dropmissing!(df)

throws and error, but  
df = dropmissing!(copy(df))

works! That seems really redundant. The strange thing is that I can execute the simple examples in the help, but when I have a dataframe with a larger number of missing values it acts up. Does this look like something that should be opened as an issue, or was there some syntax change maybe I am not aware of?

---

<div class="post-metadata">

**Author:** ![pdeffebach](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/pdeffebach/32/10320_2.png) [@pdeffebach](https://discourse.julialang.org/u/pdeffebach)\
**Post date:** [September 25, 2020, 7:35pm UTC](https://discourse.julialang.org/t/dropmissing-on-a-dataframe-causes-segfault/47101/9 "2020-09-25T19:35:23Z")

</div>

Yes please open an issue. The issue definitely has to do with `SentinalArrays`, when those kinds of arrays are copied they become normal arrays. This is why `copy` fixes things.